diff --git a/proxy/common/constants.py b/proxy/common/constants.py
index bd0a40e785..9727143b9b 100644
--- a/proxy/common/constants.py
+++ b/proxy/common/constants.py
@@ -114,6 +114,8 @@ def _env_threadless_compliant() -> bool:
     '{response_bytes} bytes - {connection_time_ms}ms'
 DEFAULT_REVERSE_PROXY_ACCESS_LOG_FORMAT = '{client_ip}:{client_port} - ' + \
     '{request_method} {request_path} -> {upstream_proxy_pass} - {connection_time_ms}ms'
+DEFAULT_LISTENER_POOL_KLASS = 'proxy.core.listener.pool.ListenerPool'
+DEFAULT_ACCEPTOR_POOL_KLASS = 'proxy.core.acceptor.pool.AcceptorPool'
 DEFAULT_NUM_ACCEPTORS = 0
 DEFAULT_NUM_WORKERS = 0
 DEFAULT_OPEN_FILE_LIMIT = 1024
@@ -127,6 +129,7 @@ def _env_threadless_compliant() -> bool:
 DEFAULT_STATIC_SERVER_DIR = os.path.join(PROXY_PY_DIR, "public")
 DEFAULT_MIN_COMPRESSION_LENGTH = 20  # In bytes
 DEFAULT_THREADLESS = _env_threadless_compliant()
+DEFAULT_THREADLESS_POOL_KLASS = 'proxy.core.work.pool.ThreadlessPool'
 DEFAULT_LOCAL_EXECUTOR = True
 DEFAULT_TIMEOUT = 10.0
 DEFAULT_VERSION = False
diff --git a/proxy/common/flag.py b/proxy/common/flag.py
index f8395a6f62..5d3c986a38 100644
--- a/proxy/common/flag.py
+++ b/proxy/common/flag.py
@@ -138,6 +138,24 @@ def initialize(
             if isinstance(work_klass, str) \
             else work_klass
 
+        # Load acceptor_pool_klass
+        acceptor_pool_klass = opts.get('acceptor_pool_klass', args.acceptor_pool_klass)
+        acceptor_pool_klass = Plugins.importer(bytes_(acceptor_pool_klass))[0] \
+            if isinstance(acceptor_pool_klass, str) \
+            else acceptor_pool_klass
+
+        # Load listener_pool_klass
+        listener_pool_klass = opts.get('listener_pool_klass', args.listener_pool_klass)
+        listener_pool_klass = Plugins.importer(bytes_(listener_pool_klass))[0] \
+            if isinstance(listener_pool_klass, str) \
+            else listener_pool_klass
+
+        # Load threadless_pool_klass
+        threadless_pool_klass = opts.get('threadless_pool_klass', args.threadless_pool_klass)
+        threadless_pool_klass = Plugins.importer(bytes_(threadless_pool_klass))[0] \
+            if isinstance(threadless_pool_klass, str) \
+            else threadless_pool_klass
+
         # TODO: Plugin flag initialization logic must be moved within plugins.
         #
         # Generate auth_code required for basic authentication if enabled
@@ -201,6 +219,8 @@ def initialize(
         # def option(t: object, key: str, default: Any) -> Any:
         #     return cast(t, opts.get(key, default))
         args.work_klass = work_klass
+        args.acceptor_pool_klass = acceptor_pool_klass
+        args.listener_pool_klass = listener_pool_klass
         args.plugins = plugins
         args.auth_code = cast(
             Optional[bytes],
@@ -376,6 +396,7 @@ def initialize(
         # evaluates to False.
         args.threadless = cast(bool, opts.get('threadless', args.threadless))
         args.threadless = is_threadless(args.threadless, args.threaded)
+        args.threadless_pool_klass = threadless_pool_klass
 
         args.pid_file = cast(
             Optional[str], opts.get(
diff --git a/proxy/core/acceptor/pool.py b/proxy/core/acceptor/pool.py
index 09fb9f447f..19871cef39 100644
--- a/proxy/core/acceptor/pool.py
+++ b/proxy/core/acceptor/pool.py
@@ -24,7 +24,9 @@
 from .acceptor import Acceptor
 from ..listener import ListenerPool
 from ...common.flag import flags
-from ...common.constants import DEFAULT_NUM_ACCEPTORS
+from ...common.constants import (
+    DEFAULT_NUM_ACCEPTORS, DEFAULT_ACCEPTOR_POOL_KLASS,
+)
 
 
 if TYPE_CHECKING:   # pragma: no cover
@@ -33,6 +35,14 @@
 logger = logging.getLogger(__name__)
 
 
+flags.add_argument(
+    '--acceptor-pool-klass',
+    type=str,
+    default=DEFAULT_ACCEPTOR_POOL_KLASS,
+    help='Default: ' + DEFAULT_ACCEPTOR_POOL_KLASS +
+    '.  Acceptor pool klass.',
+)
+
 flags.add_argument(
     '--num-acceptors',
     type=int,
diff --git a/proxy/core/listener/pool.py b/proxy/core/listener/pool.py
index b362ae558c..aef0b724fd 100644
--- a/proxy/core/listener/pool.py
+++ b/proxy/core/listener/pool.py
@@ -13,12 +13,23 @@
 
 from .tcp import TcpSocketListener
 from .unix import UnixSocketListener
+from ...common.flag import flags
+from ...common.constants import DEFAULT_LISTENER_POOL_KLASS
 
 
 if TYPE_CHECKING:   # pragma: no cover
     from .base import BaseListener
 
 
+flags.add_argument(
+    '--listener-pool-klass',
+    type=str,
+    default=DEFAULT_LISTENER_POOL_KLASS,
+    help='Default: ' + DEFAULT_LISTENER_POOL_KLASS +
+    '.  Listener pool klass.',
+)
+
+
 class ListenerPool:
     """Provides abstraction around starting multiple listeners
     based upon flags."""
diff --git a/proxy/core/work/pool.py b/proxy/core/work/pool.py
index 5458f0a89d..12d738f2c0 100644
--- a/proxy/core/work/pool.py
+++ b/proxy/core/work/pool.py
@@ -15,7 +15,9 @@
 from multiprocessing import connection
 
 from ...common.flag import flags
-from ...common.constants import DEFAULT_THREADLESS, DEFAULT_NUM_WORKERS
+from ...common.constants import (
+    DEFAULT_THREADLESS, DEFAULT_NUM_WORKERS, DEFAULT_THREADLESS_POOL_KLASS,
+)
 
 
 if TYPE_CHECKING:   # pragma: no cover
@@ -54,6 +56,14 @@
     help='Defaults to number of CPU cores.',
 )
 
+flags.add_argument(
+    '--threadless-pool-klass',
+    type=str,
+    default=DEFAULT_THREADLESS_POOL_KLASS,
+    help='Default: ' + DEFAULT_THREADLESS_POOL_KLASS +
+    '.  Threadless pool klass.',
+)
+
 
 class ThreadlessPool:
     """Manages lifecycle of threadless pool and delegates work to them
diff --git a/proxy/proxy.py b/proxy/proxy.py
index d9d9f89798..3b4e23fa0c 100644
--- a/proxy/proxy.py
+++ b/proxy/proxy.py
@@ -199,7 +199,10 @@ def setup(self) -> None:
         self._write_pid_file()
         # We setup listeners first because of flags.port override
         # in case of ephemeral port being used
-        self.listeners = ListenerPool(flags=self.flags)
+        self.listeners = cast(
+            'ListenerPool',
+            self.flags.listener_pool_klass(flags=self.flags),
+        )
         self.listeners.setup()
         # Override flags.port to match the actual port
         # we are listening upon.  This is necessary to preserve
@@ -234,20 +237,26 @@ def setup(self) -> None:
         # Setup remote executors only if
         # --local-executor mode isn't enabled.
         if self.remote_executors_enabled:
-            self.executors = ThreadlessPool(
-                flags=self.flags,
-                event_queue=event_queue,
-                executor_klass=RemoteFdExecutor,
+            self.executors = cast(
+                'ThreadlessPool',
+                self.flags.threadless_pool_klass(
+                    flags=self.flags,
+                    event_queue=event_queue,
+                    executor_klass=RemoteFdExecutor,
+                ),
             )
             self.executors.setup()
         # Setup acceptors
-        self.acceptors = AcceptorPool(
-            flags=self.flags,
-            listeners=self.listeners,
-            executor_queues=self.executors.work_queues if self.executors else [],
-            executor_pids=self.executors.work_pids if self.executors else [],
-            executor_locks=self.executors.work_locks if self.executors else [],
-            event_queue=event_queue,
+        self.acceptors = cast(
+            'AcceptorPool',
+            self.flags.acceptor_pool_klass(
+                flags=self.flags,
+                listeners=self.listeners,
+                executor_queues=self.executors.work_queues if self.executors else [],
+                executor_pids=self.executors.work_pids if self.executors else [],
+                executor_locks=self.executors.work_locks if self.executors else [],
+                event_queue=event_queue,
+            ),
         )
         self.acceptors.setup()
         # Start SSH tunnel acceptor if enabled