diff --git a/ledger/v1/msg.proto b/ledger/v1/msg.proto
new file mode 100644
index 0000000..b027852
--- /dev/null
+++ b/ledger/v1/msg.proto
@@ -0,0 +1,168 @@
+syntax = "proto3";
+
+package ledger.v1;
+
+import "google/protobuf/timestamp.proto";
+
+enum AccountClass {
+  ACCOUNT_CLASS_UNSPECIFIED = 0;
+  ACCOUNT_CLASS_USER_AVAILABLE = 1;
+  ACCOUNT_CLASS_USER_FROZEN = 2;
+  ACCOUNT_CLASS_EXTERNAL_BLOCKCHAIN = 3;
+  ACCOUNT_CLASS_TREASURY = 4;
+  ACCOUNT_CLASS_MARKET_CLEARING = 5;
+  ACCOUNT_CLASS_IPG_CLEARING = 6;
+  ACCOUNT_CLASS_COMMISSION_REVENUE = 7;
+}
+
+enum TransactionState {
+  TRANSACTION_STATE_UNSPECIFIED = 0;
+  TRANSACTION_STATE_CREATED = 1;
+  TRANSACTION_STATE_PENDING_TRANSACTION = 2;
+  TRANSACTION_STATE_PENDING_ADMIN = 3;
+  TRANSACTION_STATE_SUCCESSFUL = 4;
+  TRANSACTION_STATE_FAILED = 5;
+  TRANSACTION_STATE_SUSPENDED = 6;
+}
+
+message AccountReference {
+  AccountClass account_class = 1;
+  string owner_type = 2;
+  string owner_id = 3;
+  int64 asset_id = 4;
+}
+
+message JournalEntry {
+  uint32 line_number = 1;
+  AccountReference account = 2;
+  // Canonical base-10 decimal. Positive is credit and negative is debit.
+  string amount = 3;
+  string description = 4;
+}
+
+message BlockchainReference {
+  string network = 1;
+  string transaction_hash = 2;
+  string ledger_sequence = 3;
+}
+
+message Journal {
+  string journal_id = 1;
+  string source_service = 2;
+  string idempotency_key = 3;
+  string source_transaction_id = 4;
+  string tracking_code = 5;
+  string effect_kind = 6;
+  uint32 event_version = 7;
+  repeated JournalEntry entries = 8;
+  optional string reversal_of_journal_id = 9;
+  google.protobuf.Timestamp occurred_at = 10;
+  google.protobuf.Timestamp recorded_at = 11;
+  string correlation_id = 12;
+  string actor_id = 13;
+  BlockchainReference blockchain = 14;
+  map<string, string> metadata = 15;
+  string payload_hash = 16;
+}
+
+message AppendJournalRequest {
+  string source_service = 1;
+  string idempotency_key = 2;
+  string source_transaction_id = 3;
+  string tracking_code = 4;
+  string effect_kind = 5;
+  uint32 event_version = 6;
+  repeated JournalEntry entries = 7;
+  optional string reversal_of_journal_id = 8;
+  google.protobuf.Timestamp occurred_at = 9;
+  string correlation_id = 10;
+  string actor_id = 11;
+  BlockchainReference blockchain = 12;
+  map<string, string> metadata = 13;
+}
+
+message AppendJournalResponse {
+  Journal journal = 1;
+  bool already_existed = 2;
+}
+
+message AppendTransactionEventRequest {
+  string source_service = 1;
+  string idempotency_key = 2;
+  string source_transaction_id = 3;
+  string tracking_code = 4;
+  uint32 event_version = 5;
+  TransactionState state = 6;
+  string error_code = 7;
+  string error_message = 8;
+  google.protobuf.Timestamp occurred_at = 9;
+  string correlation_id = 10;
+  string actor_id = 11;
+  BlockchainReference blockchain = 12;
+  map<string, string> metadata = 13;
+}
+
+message TransactionEvent {
+  string event_id = 1;
+  AppendTransactionEventRequest event = 2;
+  google.protobuf.Timestamp recorded_at = 3;
+  string payload_hash = 4;
+}
+
+message AppendTransactionEventResponse {
+  TransactionEvent event = 1;
+  bool already_existed = 2;
+}
+
+message GetJournalRequest {
+  oneof lookup {
+    string journal_id = 1;
+    string idempotency_key = 2;
+  }
+}
+
+message ListEntriesRequest {
+  optional AccountReference account = 1;
+  optional int64 asset_id = 2;
+  google.protobuf.Timestamp recorded_from = 3;
+  google.protobuf.Timestamp recorded_to = 4;
+  uint32 page_size = 5;
+  string page_token = 6;
+}
+
+message ListEntriesResponse {
+  repeated Journal journals = 1;
+  string next_page_token = 2;
+}
+
+message GetBalanceRequest {
+  AccountReference account = 1;
+  google.protobuf.Timestamp as_of = 2;
+}
+
+message GetBalanceResponse {
+  AccountReference account = 1;
+  // Canonical base-10 decimal reconstructed from immutable entries.
+  string balance = 2;
+  google.protobuf.Timestamp as_of = 3;
+}
+
+message ReplayJournalsRequest {
+  // Each item is independently atomic and uses normal append idempotency.
+  repeated AppendJournalRequest journals = 1;
+}
+
+message ReplayJournalResult {
+  string idempotency_key = 1;
+  Journal journal = 2;
+  bool already_existed = 3;
+}
+
+message ReplayJournalsResponse {
+  repeated ReplayJournalResult results = 1;
+}
+
+message HealthResponse {
+  bool serving = 1;
+  bool database_ready = 2;
+}
diff --git a/ledger/v1/srv.proto b/ledger/v1/srv.proto
new file mode 100644
index 0000000..439d5ca
--- /dev/null
+++ b/ledger/v1/srv.proto
@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package ledger.v1;
+
+import "base/v1/msg.proto";
+import "ledger/v1/msg.proto";
+
+service GeneralLedgerService {
+  rpc Health(base.v1.Empty) returns (HealthResponse);
+  rpc AppendJournal(AppendJournalRequest) returns (AppendJournalResponse);
+  rpc AppendTransactionEvent(AppendTransactionEventRequest) returns (AppendTransactionEventResponse);
+  rpc GetJournal(GetJournalRequest) returns (Journal);
+  rpc ListEntries(ListEntriesRequest) returns (ListEntriesResponse);
+  rpc GetBalance(GetBalanceRequest) returns (GetBalanceResponse);
+  rpc ReplayJournals(ReplayJournalsRequest) returns (ReplayJournalsResponse);
+}