diff --git a/spec/schemas/register_file_schema.json b/spec/schemas/register_file_schema.json
new file mode 100644
index 000000000..50ef23dc1
--- /dev/null
+++ b/spec/schemas/register_file_schema.json
@@ -0,0 +1,130 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+
+  "title": "Register File Schema",
+  "description": "Schema for describing a register file",
+
+  "$defs": {
+    "register_entry": {
+      "type": "object",
+      "required": ["name"],
+      "additionalProperties": false,
+      "properties": {
+        "name": {
+          "$ref": "schema_defs.json#/$defs/register_name"
+        },
+        "abi_mnemonics": {
+          "type": "array",
+          "items": {
+            "$ref": "schema_defs.json#/$defs/register_alias"
+          },
+          "minItems": 1,
+          "uniqueItems": true,
+          "description": "ABI mnemonic names for the register"
+        },
+        "description": {
+          "$ref": "schema_defs.json#/$defs/spec_text"
+        },
+        "when": {
+          "$ref": "schema_defs.json#/$defs/requires_entry"
+        },
+        "sw_read()": {
+          "type": "string",
+          "description": "Function that returns the value of the register when read by software. Use this to define special behavior for registers (e.g., x0 always reads as zero)."
+        },
+        "sw_write(value)": {
+          "type": "string",
+          "description": "Function implementing custom write behavior for the register. Given a 'value', return either the value to be written or a modified value. Use this to define special behavior for registers (e.g., x0 ignores writes)."
+        },
+        "caller_saved": {
+          "type": "boolean",
+          "default": false,
+          "description": "Whether the register is caller-saved"
+        },
+        "callee_saved": {
+          "type": "boolean",
+          "default": false,
+          "description": "Whether the register is callee-saved"
+        },
+        "roles": {
+          "type": "array",
+          "items": {
+            "type": "string",
+            "enum": [
+              "zero",
+              "return_address",
+              "stack_pointer",
+              "global_pointer",
+              "thread_pointer",
+              "frame_pointer",
+              "return_value",
+              "argument",
+              "temporary"
+            ]
+          },
+          "uniqueItems": true
+        },
+        "writable": {
+          "type": "boolean",
+          "default": true,
+          "description": "Whether the register is writable. If false, no sw_write() method is needed."
+        }
+      }
+    },
+    "register_file": {
+      "type": "object",
+      "required": [
+        "$schema",
+        "kind",
+        "name",
+        "long_name",
+        "description",
+        "register_length",
+        "registers"
+      ],
+      "additionalProperties": false,
+      "properties": {
+        "$schema": {
+          "type": "string",
+          "format": "uri-reference",
+          "const": "register_file_schema.json#",
+          "description": "Path to schema, relative to <UDB ROOT>/schemas"
+        },
+        "kind": {
+          "type": "string",
+          "const": "register_file"
+        },
+        "name": {
+          "$ref": "schema_defs.json#/$defs/register_file_name"
+        },
+        "long_name": {
+          "type": "string"
+        },
+        "description": {
+          "$ref": "schema_defs.json#/$defs/spec_text"
+        },
+        "definedBy": {
+          "$ref": "schema_defs.json#/$defs/requires_entry"
+        },
+        "register_class": {
+          "type": "string",
+          "enum": ["general_purpose", "floating_point", "vector"]
+        },
+        "register_length": {
+          "$ref": "schema_defs.json#/$defs/bit_length_value"
+        },
+        "registers": {
+          "type": "array",
+          "minItems": 1,
+          "items": {
+            "$ref": "#/$defs/register_entry"
+          }
+        },
+        "$source": {
+          "type": "string",
+          "format": "uri-reference"
+        }
+      }
+    }
+  }
+}
diff --git a/spec/schemas/schema_defs.json b/spec/schemas/schema_defs.json
index 3b2ed7d73..a5196cd0a 100644
--- a/spec/schemas/schema_defs.json
+++ b/spec/schemas/schema_defs.json
@@ -43,6 +43,35 @@
       ],
       "description": "Location of a field in a register"
     },
+    "bit_length_value": {
+      "description": "Bit width value for a register or field",
+      "oneOf": [
+        {
+          "type": "integer",
+          "minimum": 1
+        },
+        {
+          "type": "string",
+          "minLength": 1,
+          "enum": ["MXLEN"]
+        }
+      ]
+    },
+    "register_name": {
+      "type": "string",
+      "pattern": "^[A-Za-z][A-Za-z0-9_.-]*$",
+      "description": "Register name"
+    },
+    "register_file_name": {
+      "type": "string",
+      "pattern": "^[A-Za-z]$",
+      "description": "Register file name"
+    },
+    "register_alias": {
+      "type": "string",
+      "pattern": "^[A-Za-z][A-Za-z0-9_.-]*$",
+      "description": "Register alias or ABI mnemonic"
+    },
     "possibly_split_field_location": {
       "description": "Location specifier for a field",
       "oneOf": [
diff --git a/spec/std/isa/README.adoc b/spec/std/isa/README.adoc
index 809631ea8..88e71d85f 100644
--- a/spec/std/isa/README.adoc
+++ b/spec/std/isa/README.adoc
@@ -29,8 +29,8 @@ Three standard configs are present:
  * `rv64`: A configuration where only `MXLEN` is known to be 64, i.e., the RV64 ISA.
 
 The architecture is specified in a series of https://en.wikipedia.org/wiki/YAML[YAML]
-files for _Extensions_, _Instructions_, and _Control and Status Registers (CSRs)_.
-Each extension/instruction/CSR has its own file.
+files for _Extensions_, _Instructions_, _RegFiles_, and _Control and Status Registers (CSRs)_.
+Each extension/instruction/regfile/CSR has its own file.
 
 == Flow
 
@@ -142,6 +142,40 @@ H: # <1>
 
 === Instructions
 
+=== Register Files
+
+.Example register file specification
+[source,yaml]
+----
+$schema: register_file_schema.json#
+kind: register_file
+name: X
+long_name: Integer General Purpose Registers
+definedBy: I
+register_class: general_purpose
+register_length: MXLEN # <1>
+registers:
+  - name: x0    # <2>
+    abi_mnemonics: [zero] # <3>
+    roles: [zero]
+    sw_read(): | # <4>
+      return 0;
+    sw_write(value): |
+      # x0 ignores all writes
+  - name: x1
+    abi_mnemonics: [ra]
+    roles: [return_address]
+  - name: x8
+    abi_mnemonics: [s0, fp] # <5>
+    roles: [callee_saved, frame_pointer]
+----
+
+<1> The registers in a register file have identical fixed widths, either an explicit width or from a parameter (e.g. MXLEN or VLEN).
+<2> Each register has a unique name (e.g., x0, x1, x2, etc.). The register's index is inferred from its position in the array (starting from 0).
+<3> Registers can optionally have ABI mnemonics (e.g., ra, sp, fp, etc.).
+<4> Individual registers can define `sw_read()` and `sw_write()` for special behavior (e.g., x0 hardwired to zero).
+<5> A register can have multiple ABI mnemonics (e.g., x8 is known as both s0 and fp).
+
 [source,yaml]
 ----
 add: # <1>
diff --git a/spec/std/isa/register_file/X.yaml b/spec/std/isa/register_file/X.yaml
new file mode 100644
index 000000000..33e971190
--- /dev/null
+++ b/spec/std/isa/register_file/X.yaml
@@ -0,0 +1,200 @@
+# Copyright (c) Animesh Agarwal
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+
+# yaml-language-server: $schema=../../../../schemas/register_file_schema.json
+
+$schema: register_file_schema.json#
+kind: register_file
+name: X
+long_name: General Purpose Registers
+description: |
+  The 'X' register file contains the general-purpose integer registers. Each register
+  is MXLEN bits wide, unless XLEN<MXLEN. Register 'x0' is hardwired to zero, while
+  the remaining registers hold architecturally visible integer state used by the
+  calling convention and execution environment.
+definedBy: I
+register_class: general_purpose
+register_length: MXLEN
+registers:
+  - name: x0
+    abi_mnemonics: [zero]
+    roles: [zero]
+    writable: false
+    description: |
+      Register x0 is hardwired with all bits equal to 0.
+    sw_read(): |
+      return 0;
+  - name: x1
+    abi_mnemonics: [ra]
+    caller_saved: true
+    roles: [return_address]
+    description: Return address register used by CALL/JAL instructions.
+  - name: x2
+    abi_mnemonics: [sp]
+    callee_saved: true
+    roles: [stack_pointer]
+    description: Stack pointer.
+  - name: x3
+    abi_mnemonics: [gp]
+    roles: [global_pointer]
+    description: Global pointer.
+  - name: x4
+    abi_mnemonics: [tp]
+    roles: [thread_pointer]
+    description: Thread pointer or TLS base.
+  - name: x5
+    abi_mnemonics: [t0]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register / linkage scratch.
+  - name: x6
+    abi_mnemonics: [t1]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+  - name: x7
+    abi_mnemonics: [t2]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+  - name: x8
+    abi_mnemonics: [s0, fp]
+    callee_saved: true
+    roles: [frame_pointer]
+    description: Callee-saved register; used as frame pointer when required.
+  - name: x9
+    abi_mnemonics: [s1]
+    callee_saved: true
+    description: Callee-saved register.
+  - name: x10
+    abi_mnemonics: [a0]
+    caller_saved: true
+    roles: [argument, return_value]
+    description: Function argument / return value register 0.
+  - name: x11
+    abi_mnemonics: [a1]
+    caller_saved: true
+    roles: [argument, return_value]
+    description: Function argument / return value register 1.
+  - name: x12
+    abi_mnemonics: [a2]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 2.
+  - name: x13
+    abi_mnemonics: [a3]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 3.
+  - name: x14
+    abi_mnemonics: [a4]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 4.
+  - name: x15
+    abi_mnemonics: [a5]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 5.
+  - name: x16
+    abi_mnemonics: [a6]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 6.
+    when:
+      not: { name: E }
+  - name: x17
+    abi_mnemonics: [a7]
+    caller_saved: true
+    roles: [argument]
+    description: Function argument register 7 / syscall ID.
+    when:
+      not: { name: E }
+  - name: x18
+    abi_mnemonics: [s2]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x19
+    abi_mnemonics: [s3]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x20
+    abi_mnemonics: [s4]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x21
+    abi_mnemonics: [s5]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x22
+    abi_mnemonics: [s6]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x23
+    abi_mnemonics: [s7]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x24
+    abi_mnemonics: [s8]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x25
+    abi_mnemonics: [s9]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x26
+    abi_mnemonics: [s10]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x27
+    abi_mnemonics: [s11]
+    callee_saved: true
+    description: Callee-saved register.
+    when:
+      not: { name: E }
+  - name: x28
+    abi_mnemonics: [t3]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+    when:
+      not: { name: E }
+  - name: x29
+    abi_mnemonics: [t4]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+    when:
+      not: { name: E }
+  - name: x30
+    abi_mnemonics: [t5]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+    when:
+      not: { name: E }
+  - name: x31
+    abi_mnemonics: [t6]
+    caller_saved: true
+    roles: [temporary]
+    description: Temporary register.
+    when:
+      not: { name: E }
diff --git a/tools/ruby-gems/udb/lib/udb/architecture.rb b/tools/ruby-gems/udb/lib/udb/architecture.rb
index 7126575fc..7b27baa59 100644
--- a/tools/ruby-gems/udb/lib/udb/architecture.rb
+++ b/tools/ruby-gems/udb/lib/udb/architecture.rb
@@ -50,6 +50,7 @@
 require_relative "obj/certificate"
 require_relative "obj/csr"
 require_relative "obj/csr_field"
+require_relative "obj/register_file"
 require_relative "exception_code"
 require_relative "obj/extension"
 require_relative "obj/instruction"
@@ -175,6 +176,12 @@ def self.generate_obj_methods(fn_name, arch_dir, obj_class)
       klass: Csr,
       kind: DatabaseObject::Kind::Csr
     },
+    {
+      fn_name: "register_file",
+      arch_dir: "register",
+      klass: RegisterFile,
+      kind: DatabaseObject::Kind::RegisterFile
+    },
     {
       fn_name: "proc_cert_class",
       arch_dir: "proc_cert_class",
diff --git a/tools/ruby-gems/udb/lib/udb/obj/database_obj.rb b/tools/ruby-gems/udb/lib/udb/obj/database_obj.rb
index 0ed0cea02..bc2c3b658 100644
--- a/tools/ruby-gems/udb/lib/udb/obj/database_obj.rb
+++ b/tools/ruby-gems/udb/lib/udb/obj/database_obj.rb
@@ -26,6 +26,7 @@ class Kind < T::Enum
       Csr = new("csr")
       CsrField = new("csr_field")
       Extension = new("extension")
+      RegisterFile = new("register_file")
       Manual = new("manual")
       ManualVersion = new("manual version")
       ProcessorCertificateClass = new("processor certificate class")
diff --git a/tools/ruby-gems/udb/lib/udb/obj/register_file.rb b/tools/ruby-gems/udb/lib/udb/obj/register_file.rb
new file mode 100644
index 000000000..129a5aa6a
--- /dev/null
+++ b/tools/ruby-gems/udb/lib/udb/obj/register_file.rb
@@ -0,0 +1,107 @@
+# Copyright (c) Animesh Agarwal
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+
+# typed: true
+# frozen_string_literal: true
+
+require_relative "database_obj"
+require_relative "../req_expression"
+
+module Udb
+
+class RegisterFile < TopLevelDatabaseObject
+  extend T::Sig
+
+  class RegisterEntry
+    extend T::Sig
+
+    class Role < T::Enum
+      enums do
+        Zero = new("zero")
+        ReturnAddress = new("return_address")
+        StackPointer = new("stack_pointer")
+        GlobalPointer = new("global_pointer")
+        ThreadPointer = new("thread_pointer")
+        FramePointer = new("frame_pointer")
+        ReturnValue = new("return_value")
+        Argument = new("argument")
+        Temporary = new("temporary")
+      end
+    end
+
+  sig { returns(T::Hash[String, T.untyped]) }
+  attr_reader :data
+
+    sig { returns(Integer) }
+    attr_reader :index
+
+    sig { params(file: RegisterFile, data: T::Hash[String, T.untyped], index: Integer).void }
+    def initialize(file, data, index)
+      @file = file
+      @data = data
+      @index = index
+    end
+
+    sig { returns(String) }
+    def name = @data.fetch("name")
+
+    sig { returns(T::Array[String]) }
+    def abi_mnemonics = @data.fetch("abi_mnemonics", [])
+
+    sig { returns(T.any(Integer, String)) }
+    def index = @index
+
+    sig { returns(T.nilable(String)) }
+    def description = @data["description"]
+
+    sig { returns(T::Array[Role]) }
+    def roles
+      @roles ||= @data.fetch("roles", []).map { |role| Role.deserialize(role) }
+    end
+
+    sig { returns(T.nilable(T::Boolean)) }
+    def caller_saved = @data["caller_saved"]
+
+    sig { returns(T.nilable(T::Boolean)) }
+    def callee_saved = @data["callee_saved"]
+
+    sig { returns(T.nilable(String)) }
+    def sw_read = @data["sw_read()"]
+
+    sig { returns(T.nilable(String)) }
+    def sw_write = @data["sw_write(value)"]
+
+    sig { returns(T.nilable(ExtensionRequirementExpression)) }
+    def defined_by_condition
+      return nil unless @data.key?("definedBy")
+
+      @defined_by_condition ||= ExtensionRequirementExpression.new(@data.fetch("definedBy"), @file.arch)
+    end
+
+    sig { returns(T.nilable(ExtensionRequirementExpression)) }
+    def when_condition
+      return nil unless @data.key?("when")
+
+      @when_condition ||= ExtensionRequirementExpression.new(@data.fetch("when"), @file.arch)
+    end
+  end
+
+  sig { returns(T.any(Integer, String)) }
+  def register_length = @data.fetch("register_length")
+
+  sig { returns(T.nilable(String)) }
+  def summary = @data["summary"]
+
+  sig { returns(T.nilable(String)) }
+  def register_class = @data["register_class"]
+
+  sig { returns(T::Array[RegisterEntry]) }
+  def registers
+    @registers ||= @data.fetch("registers", []).map.with_index { |reg, idx| RegisterEntry.new(self, reg, idx) }
+  end
+
+  sig { returns(T::Array[T::Hash[String, T.untyped]]) }
+  def templates = @data.fetch("templates", [])
+ end
+
+end