diff --git a/PostgreSQL/build_rdbms_01/Readme.md b/PostgreSQL/build_rdbms_01/Readme.md
index 7564a27..c98a37c 100644
--- a/PostgreSQL/build_rdbms_01/Readme.md
+++ b/PostgreSQL/build_rdbms_01/Readme.md
@@ -41,9 +41,10 @@ The orchestrator runs the installers in this order:
 4. pgAudit
 5. set_user
 6. pg_stat_statements
-7. pg_repack
-8. pg_stat_monitor
-9. pgvector
+7. passwordcheck
+8. pg_repack
+9. pg_stat_monitor
+10. pgvector
 
 After a successful run, the orchestrator:
 
@@ -65,6 +66,7 @@ Each component can also be installed independently. The PostgreSQL installation
 ./install_pgaudit.sh --version 18.6
 ./install_set_user.sh --version 18.6
 ./install_pg_stat_statements.sh --version 18.6
+./install_passwordcheck.sh --version 18.6
 ./install_pg_repack.sh --version 18.6
 ./install_pg_stat_monitor.sh --version 18.6
 ./install_pgvector.sh --version 18.6
@@ -119,6 +121,10 @@ Builds and installs the `set_user` extension using the selected PostgreSQL `pg_c
 
 Downloads the matching PostgreSQL source tree and builds `pg_stat_statements` from `contrib` using PGXS.
 
+### `install_passwordcheck.sh`
+
+Downloads the matching PostgreSQL source tree and builds the `passwordcheck` contrib module using PGXS. The module is loaded at server startup through `shared_preload_libraries`; it does not have a `CREATE EXTENSION` control file.
+
 ### `install_pg_repack.sh`
 
 Builds and installs the `pg_repack` extension and its `pg_repack` command-line utility.
@@ -185,13 +191,13 @@ SET_USER_TAG=REL4_2_0 \
 ./install_postgresql_extensions.sh 17.11
 ```
 
-When `CONFIG_FILE` is supplied, the orchestrator adds the extensions that require server startup loading:
+When `CONFIG_FILE` is supplied, the orchestrator adds the modules and extensions that require server startup loading:
 
 ```conf
-shared_preload_libraries = 'pg_cron,timescaledb,pgaudit,pg_stat_statements,pg_stat_monitor'
+shared_preload_libraries = 'pg_cron,timescaledb,pgaudit,pg_stat_statements,pg_stat_monitor,passwordcheck'
 ```
 
-`pg_repack` and `set_user` do not require `shared_preload_libraries`. `pg_stat_activity` is a PostgreSQL system view and is not installed as an extension.
+`pg_repack`, pgvector, and `set_user` do not require `shared_preload_libraries`. `passwordcheck` is a PostgreSQL contrib module (not a SQL extension), and `pg_stat_activity` is a built-in PostgreSQL system view.
 
 ## Prerequisites
 
diff --git a/PostgreSQL/build_rdbms_01/install_passwordcheck.sh b/PostgreSQL/build_rdbms_01/install_passwordcheck.sh
new file mode 100644
index 0000000..94c69bd
--- /dev/null
+++ b/PostgreSQL/build_rdbms_01/install_passwordcheck.sh
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+
+set -Eeuo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=install_common.sh
+source "$SCRIPT_DIR/install_common.sh"
+
+readonly STAGING_DIR="${STAGING_DIR:-$SCRIPT_DIR/tmp}"
+readonly POSTGRES_ROOT="${POSTGRES_ROOT:-/app/postgres/rdbms}"
+
+if [[ "${1:-}" == "--help" || "${1:-}" == "-h" ]]; then
+  show_help "$0" "Build and install PostgreSQL's passwordcheck module."
+  exit 0
+fi
+
+POSTGRES_VERSION="$(parse_postgresql_version "$@")"
+readonly POSTGRES_VERSION
+require_tools curl tar make
+readonly PREFIX="${PREFIX:-$POSTGRES_ROOT/$POSTGRES_VERSION}"
+readonly PG_CONFIG="$PREFIX/bin/pg_config"
+require_postgresql_installation "$PREFIX"
+reset_staging_dir "$STAGING_DIR"
+
+printf 'Building passwordcheck from PostgreSQL %s\n' "$POSTGRES_VERSION"
+readonly POSTGRES_ARCHIVE="$STAGING_DIR/postgresql-$POSTGRES_VERSION.tar.gz"
+readonly POSTGRES_SOURCE="$STAGING_DIR/postgresql-$POSTGRES_VERSION"
+curl -fL --retry 3 --retry-delay 2 \
+  -o "$POSTGRES_ARCHIVE" \
+  "https://ftp.postgresql.org/pub/source/v$POSTGRES_VERSION/postgresql-$POSTGRES_VERSION.tar.gz"
+tar -xzf "$POSTGRES_ARCHIVE" -C "$STAGING_DIR"
+
+readonly PASSWORDCHECK_SOURCE="$POSTGRES_SOURCE/contrib/passwordcheck"
+make -C "$PASSWORDCHECK_SOURCE" \
+  -j"${JOBS:-$(nproc)}" USE_PGXS=1 PG_CONFIG="$PG_CONFIG"
+make -C "$PASSWORDCHECK_SOURCE" \
+  install USE_PGXS=1 PG_CONFIG="$PG_CONFIG"
+test -f "$PREFIX/lib/passwordcheck.so"
+
+readonly SAVED_SOURCE_DIR="$(copy_install_source "$PASSWORDCHECK_SOURCE" "$PREFIX" "passwordcheck-$POSTGRES_VERSION")"
+write_install_recipe "$SAVED_SOURCE_DIR" "$POSTGRES_VERSION" "$PREFIX" <<'RECIPE'
+cd "$SCRIPT_DIR"
+
+# Configure
+# passwordcheck uses PGXS directly and does not require a separate configure step.
+
+# Make
+make -j"$JOBS" USE_PGXS=1 PG_CONFIG="$PG_CONFIG"
+
+# Make install
+make install USE_PGXS=1 PG_CONFIG="$PG_CONFIG"
+RECIPE
diff --git a/PostgreSQL/build_rdbms_01/install_postgresql_extensions.sh b/PostgreSQL/build_rdbms_01/install_postgresql_extensions.sh
index 379d746..4411668 100644
--- a/PostgreSQL/build_rdbms_01/install_postgresql_extensions.sh
+++ b/PostgreSQL/build_rdbms_01/install_postgresql_extensions.sh
@@ -152,12 +152,13 @@ mkdir -p "$SOURCES_DIR"
 "$SCRIPT_DIR/install_pgaudit.sh" --version "$POSTGRES_VERSION"
 "$SCRIPT_DIR/install_set_user.sh" --version "$POSTGRES_VERSION"
 "$SCRIPT_DIR/install_pg_stat_statements.sh" --version "$POSTGRES_VERSION"
+"$SCRIPT_DIR/install_passwordcheck.sh" --version "$POSTGRES_VERSION"
 "$SCRIPT_DIR/install_pg_repack.sh" --version "$POSTGRES_VERSION"
 "$SCRIPT_DIR/install_pg_stat_monitor.sh" --version "$POSTGRES_VERSION"
 "$SCRIPT_DIR/install_pgvector.sh" --version "$POSTGRES_VERSION"
 
 readonly CONFIG_FILE="${CONFIG_FILE:-}"
-readonly SHARED_PRELOAD_LIBRARIES="pg_cron,timescaledb,pgaudit,pg_stat_statements,pg_stat_monitor"
+readonly SHARED_PRELOAD_LIBRARIES="pg_cron,timescaledb,pgaudit,pg_stat_statements,pg_stat_monitor,passwordcheck"
 
 if [[ -n "$CONFIG_FILE" ]]; then
   [[ -f "$CONFIG_FILE" ]] || {
@@ -173,7 +174,7 @@ path = pathlib.Path(sys.argv[1])
 text = path.read_text()
 pattern = r"(?m)^[ \t]*(#?)[ \t]*shared_preload_libraries[ \t]*=[ \t]*'([^']*)'[^\n]*$"
 match = re.search(pattern, text)
-required = ("pg_cron", "timescaledb", "pgaudit", "pg_stat_statements", "pg_stat_monitor")
+required = ("pg_cron", "timescaledb", "pgaudit", "pg_stat_statements", "pg_stat_monitor", "passwordcheck")
 if match:
     libraries = [item.strip() for item in match.group(2).split(",") if item.strip()]
     for library in required:
@@ -206,6 +207,7 @@ printf '  TimescaleDB: %s\n' "$(extension_version timescaledb)"
 printf '  pgaudit: %s\n' "$(extension_version pgaudit)"
 printf '  set_user: %s\n' "$(extension_version set_user)"
 printf '  pg_stat_statements: %s\n' "$(extension_version pg_stat_statements)"
+printf '  passwordcheck: PostgreSQL %s contrib module\n' "$POSTGRES_VERSION"
 printf '  pg_repack: %s\n' "$(extension_version pg_repack)"
 printf '  pg_stat_monitor: %s\n' "$(extension_version pg_stat_monitor)"
 printf '  pgvector: %s\n' "$(extension_version vector)"