diff --git a/Cargo.lock b/Cargo.lock
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -211,6 +211,7 @@
 name = "chronik-lib"
 version = "0.1.0"
 dependencies = [
+ "abc-rust-error",
  "abc-rust-lint",
  "chronik-bridge",
  "chronik-util",
diff --git a/chronik/CMakeLists.txt b/chronik/CMakeLists.txt
--- a/chronik/CMakeLists.txt
+++ b/chronik/CMakeLists.txt
@@ -115,6 +115,7 @@
 # chronik::Stop to run the indexer from C++.
 add_library(chronik
     chronik-cpp/chronik.cpp
+    chronik-cpp/chronik_validationinterface.cpp
     ${CHRONIK_LIB_GENERATED_CPP_FILES}
 )
 target_link_libraries(chronik
diff --git a/chronik/chronik-cpp/chronik.cpp b/chronik/chronik-cpp/chronik.cpp
--- a/chronik/chronik-cpp/chronik.cpp
+++ b/chronik/chronik-cpp/chronik.cpp
@@ -7,17 +7,21 @@
 #include <node/context.h>
 
 #include <chronik-cpp/chronik.h>
+#include <chronik-cpp/chronik_validationinterface.h>
 #include <chronik-lib/src/ffi.rs.h>
 
 namespace chronik {
 
 void Start([[maybe_unused]] const Config &config,
            [[maybe_unused]] const NodeContext &node) {
-    chronik_bridge::setup_bridge();
+    rust::Box<chronik_bridge::Chronik> chronik_box =
+        chronik_bridge::setup_bridge();
+    StartChronikValidationInterface(std::move(chronik_box));
 }
 
 void Stop() {
     LogPrintf("Stopping Chronik...\n");
+    StopChronikValidationInterface();
 }
 
 } // namespace chronik
diff --git a/chronik/chronik-cpp/chronik_validationinterface.h b/chronik/chronik-cpp/chronik_validationinterface.h
new file mode 100644
--- /dev/null
+++ b/chronik/chronik-cpp/chronik_validationinterface.h
@@ -0,0 +1,22 @@
+// Copyright (c) 2022 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <rust/cxx.h>
+
+#ifndef BITCOIN_CHRONIK_CPP_CHRONIK_VALIDATIONINTERFACE_H
+#define BITCOIN_CHRONIK_CPP_CHRONIK_VALIDATIONINTERFACE_H
+
+namespace chronik_bridge {
+struct Chronik;
+} // namespace chronik_bridge
+
+namespace chronik {
+
+void StartChronikValidationInterface(
+    rust::Box<chronik_bridge::Chronik> chronik_box);
+
+void StopChronikValidationInterface();
+} // namespace chronik
+
+#endif // BITCOIN_CHRONIK_CPP_CHRONIK_VALIDATIONINTERFACE_H
diff --git a/chronik/chronik-cpp/chronik_validationinterface.cpp b/chronik/chronik-cpp/chronik_validationinterface.cpp
new file mode 100644
--- /dev/null
+++ b/chronik/chronik-cpp/chronik_validationinterface.cpp
@@ -0,0 +1,59 @@
+// Copyright (c) 2022 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <chronik-lib/src/ffi.rs.h>
+#include <validationinterface.h>
+
+namespace chronik {
+
+class ChronikValidationInterface final : public CValidationInterface {
+public:
+    ChronikValidationInterface(rust::Box<chronik_bridge::Chronik> chronik_box)
+        : m_chronik(std::move(chronik_box)) {}
+
+    void Register() { RegisterValidationInterface(this); }
+
+    void Unregister() { UnregisterValidationInterface(this); }
+
+private:
+    rust::Box<chronik_bridge::Chronik> m_chronik;
+
+    void TransactionAddedToMempool(const CTransactionRef &ptx,
+                                   uint64_t mempool_sequence) override {
+        m_chronik->handle_tx_added_to_mempool();
+    }
+
+    void TransactionRemovedFromMempool(const CTransactionRef &ptx,
+                                       MemPoolRemovalReason reason,
+                                       uint64_t mempool_sequence) override {
+        m_chronik->handle_tx_removed_from_mempool();
+    }
+
+    void BlockConnected(const std::shared_ptr<const CBlock> &block,
+                        const CBlockIndex *pindex) override {
+        m_chronik->handle_block_connected();
+    }
+
+    void BlockDisconnected(const std::shared_ptr<const CBlock> &block,
+                           const CBlockIndex *pindex) override {
+        m_chronik->handle_block_disconnected();
+    }
+};
+
+std::unique_ptr<ChronikValidationInterface> g_chronik_validation_interface;
+
+void StartChronikValidationInterface(
+    rust::Box<chronik_bridge::Chronik> chronik_box) {
+    g_chronik_validation_interface =
+        std::make_unique<ChronikValidationInterface>(std::move(chronik_box));
+    g_chronik_validation_interface->Register();
+}
+
+void StopChronikValidationInterface() {
+    g_chronik_validation_interface->Unregister();
+    // Reset so the Box is dropped and all handles are released.
+    g_chronik_validation_interface.reset();
+}
+
+} // namespace chronik
diff --git a/chronik/chronik-lib/Cargo.toml b/chronik/chronik-lib/Cargo.toml
--- a/chronik/chronik-lib/Cargo.toml
+++ b/chronik/chronik-lib/Cargo.toml
@@ -13,6 +13,7 @@
 
 [dependencies]
 abc-rust-lint = { path = "../abc-rust-lint" }
+abc-rust-error = { path = "../abc-rust-error" }
 chronik-bridge = { path = "../chronik-bridge" }
 chronik-util = { path = "../chronik-util" }
 
diff --git a/chronik/chronik-lib/src/bridge.rs b/chronik/chronik-lib/src/bridge.rs
--- a/chronik/chronik-lib/src/bridge.rs
+++ b/chronik/chronik-lib/src/bridge.rs
@@ -4,13 +4,39 @@
 
 //! Rust side of the bridge; these structs and functions are exposed to C++.
 
+use abc_rust_error::Result;
 use chronik_util::{log, log_chronik};
 
-/// Setup the Chronik bridge. Currently only logs to bitcoind.
-pub fn setup_bridge() {
+/// Setup the Chronik bridge. Returns a ChronikIndexer object.
+pub fn setup_bridge() -> Result<Box<Chronik>> {
     log!("Starting Chronik...\n");
-    log_chronik!(
-        "Note: Chronik is not implemented yet. These logs are just for \
-         testing.\n"
-    );
+    Ok(Box::new(Chronik))
+}
+
+/// Contains all db, runtime, tpc, etc. handles needed by Chronik.
+/// This makes it so when this struct is dropped, all handles are relased
+/// cleanly.
+#[derive(Debug)]
+pub struct Chronik;
+
+impl Chronik {
+    /// Tx added to the bitcoind mempool
+    pub fn handle_tx_added_to_mempool(&self) {
+        log_chronik!("Chronik: transaction added to mempool\n");
+    }
+
+    /// Tx removed from the bitcoind mempool
+    pub fn handle_tx_removed_from_mempool(&self) {
+        log_chronik!("Chronik: transaction removed from mempool\n");
+    }
+
+    /// Block connected to the longest chain
+    pub fn handle_block_connected(&self) {
+        log_chronik!("Chronik: block connected\n");
+    }
+
+    /// Block disconnected from the longest chain
+    pub fn handle_block_disconnected(&self) {
+        log_chronik!("Chronik: block disconnected\n");
+    }
 }
diff --git a/chronik/chronik-lib/src/ffi.rs b/chronik/chronik-lib/src/ffi.rs
--- a/chronik/chronik-lib/src/ffi.rs
+++ b/chronik/chronik-lib/src/ffi.rs
@@ -5,12 +5,18 @@
 //! Module containing the cxx definitions for the bridge from Rust to C++.
 
 pub use self::ffi_inner::*;
-use crate::bridge::setup_bridge;
+use crate::bridge::{setup_bridge, Chronik};
 
 #[allow(unsafe_code)]
 #[cxx::bridge(namespace = "chronik_bridge")]
 mod ffi_inner {
     extern "Rust" {
-        fn setup_bridge();
+        type Chronik;
+        fn setup_bridge() -> Result<Box<Chronik>>;
+
+        fn handle_tx_added_to_mempool(&self);
+        fn handle_tx_removed_from_mempool(&self);
+        fn handle_block_connected(&self);
+        fn handle_block_disconnected(&self);
     }
 }