diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# 1.1
+
+- `ReadyForUseConnectionStatus` got extended with the `ConnectionReadyForUseReason` details.
+- `initSession` setting added.
+
 # 1
 
 - Optional observability event stream added. Provides a flexible mechanism for monitoring the healthiness of the pool via logs and metrics.
diff --git a/diagrams-output/observation-status-model.png b/diagrams-output/observation-status-model.png
new file mode 100644
Binary files /dev/null and b/diagrams-output/observation-status-model.png differ
diff --git a/hasql-pool.cabal b/hasql-pool.cabal
--- a/hasql-pool.cabal
+++ b/hasql-pool.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name: hasql-pool
-version: 1.0.1
+version: 1.1
 category: Hasql, Database, PostgreSQL
 synopsis: Pool of connections for Hasql
 homepage: https://github.com/nikita-volkov/hasql-pool
@@ -10,8 +10,13 @@
 copyright: (c) 2015, Nikita Volkov
 license: MIT
 license-file: LICENSE
-extra-source-files: CHANGELOG.md
+extra-source-files:
+  CHANGELOG.md
+  diagrams-output/*.png
 
+extra-doc-files:
+  diagrams-output/*.png
+
 source-repository head
   type: git
   location: git://github.com/nikita-volkov/hasql-pool.git
@@ -41,6 +46,8 @@
     MagicHash
     MultiParamTypeClasses
     MultiWayIf
+    NoImplicitPrelude
+    NoMonomorphismRestriction
     NumericUnderscores
     OverloadedStrings
     ParallelListComp
@@ -57,8 +64,6 @@
     TypeFamilies
     TypeOperators
     UnboxedTuples
-    NoImplicitPrelude
-    NoMonomorphismRestriction
 
   default-language: Haskell2010
 
diff --git a/src/library/exposed/Hasql/Pool.hs b/src/library/exposed/Hasql/Pool.hs
--- a/src/library/exposed/Hasql/Pool.hs
+++ b/src/library/exposed/Hasql/Pool.hs
@@ -60,7 +60,9 @@
     -- | To stop the manager thread via garbage collection.
     poolReaperRef :: IORef (),
     -- | Action for reporting the observations.
-    poolObserver :: Observation -> IO ()
+    poolObserver :: Observation -> IO (),
+    -- | Initial session to execute upon every established connection.
+    poolInitSession :: Session.Session ()
   }
 
 -- | Create a connection-pool.
@@ -98,7 +100,7 @@
     -- When the pool goes out of scope, stop the manager.
     killThread managerTid
 
-  return $ Pool (Config.size config) (Config.connectionSettingsProvider config) acqTimeoutMicros agingTimeoutNanos maxIdletimeNanos connectionQueue capVar reuseVar reaperRef (Config.observationHandler config)
+  return $ Pool (Config.size config) (Config.connectionSettingsProvider config) acqTimeoutMicros agingTimeoutNanos maxIdletimeNanos connectionQueue capVar reuseVar reaperRef (Config.observationHandler config) (Config.initSession config)
   where
     acqTimeoutMicros =
       div (fromIntegral (diffTimeToPicoseconds (Config.acquisitionTimeout config))) 1_000_000
@@ -164,15 +166,24 @@
       now <- getMonotonicTimeNSec
       id <- Uuid.nextRandom
       poolObserver (ConnectionObservation id ConnectingConnectionStatus)
-      connRes <- Connection.acquire settings
-      case connRes of
+      Connection.acquire settings >>= \case
         Left connErr -> do
           poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (fmap (Text.decodeUtf8With Text.lenientDecode) connErr))))
           atomically $ modifyTVar' poolCapacity succ
           return $ Left $ ConnectionUsageError connErr
-        Right entry -> do
-          poolObserver (ConnectionObservation id ReadyForUseConnectionStatus)
-          onLiveConn reuseVar (Entry entry now now id)
+        Right connection -> do
+          Session.run poolInitSession connection >>= \case
+            Left err -> do
+              Connection.release connection
+              case err of
+                Session.QueryError _ _ (Session.ClientError details) -> do
+                  poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (fmap (Text.decodeUtf8With Text.lenientDecode) details))))
+                _ ->
+                  poolObserver (ConnectionObservation id (TerminatedConnectionStatus (InitializationErrorTerminationReason err)))
+              return $ Left $ SessionUsageError err
+            Right () -> do
+              poolObserver (ConnectionObservation id (ReadyForUseConnectionStatus EstablishedConnectionReadyForUseReason))
+              onLiveConn reuseVar (Entry connection now now id)
 
     onConn reuseVar entry = do
       now <- getMonotonicTimeNSec
@@ -206,11 +217,11 @@
             return $ Left $ SessionUsageError err
           _ -> do
             returnConn
-            poolObserver (ConnectionObservation (entryId entry) ReadyForUseConnectionStatus)
+            poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus (SessionFailedConnectionReadyForUseReason err)))
             return $ Left $ SessionUsageError err
         Right (Right res) -> do
           returnConn
-          poolObserver (ConnectionObservation (entryId entry) ReadyForUseConnectionStatus)
+          poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus SessionSucceededConnectionReadyForUseReason))
           return $ Right res
       where
         returnConn =
diff --git a/src/library/exposed/Hasql/Pool/Config.hs b/src/library/exposed/Hasql/Pool/Config.hs
--- a/src/library/exposed/Hasql/Pool/Config.hs
+++ b/src/library/exposed/Hasql/Pool/Config.hs
@@ -10,6 +10,7 @@
     Setting.staticConnectionSettings,
     Setting.dynamicConnectionSettings,
     Setting.observationHandler,
+    Setting.initSession,
   )
 where
 
diff --git a/src/library/exposed/Hasql/Pool/Config/Defaults.hs b/src/library/exposed/Hasql/Pool/Config/Defaults.hs
--- a/src/library/exposed/Hasql/Pool/Config/Defaults.hs
+++ b/src/library/exposed/Hasql/Pool/Config/Defaults.hs
@@ -3,6 +3,7 @@
 import qualified Hasql.Connection as Connection
 import Hasql.Pool.Observation (Observation)
 import Hasql.Pool.Prelude
+import qualified Hasql.Session as Session
 
 -- |
 -- 3 connections.
@@ -38,3 +39,8 @@
 -- > const (pure ())
 observationHandler :: Observation -> IO ()
 observationHandler = const (pure ())
+
+-- |
+-- > pure ()
+initSession :: Session.Session ()
+initSession = pure ()
diff --git a/src/library/exposed/Hasql/Pool/Observation.hs b/src/library/exposed/Hasql/Pool/Observation.hs
--- a/src/library/exposed/Hasql/Pool/Observation.hs
+++ b/src/library/exposed/Hasql/Pool/Observation.hs
@@ -5,6 +5,7 @@
 module Hasql.Pool.Observation where
 
 import Hasql.Pool.Prelude
+import qualified Hasql.Session as Session
 
 -- | An observation of a change of the state of a pool.
 data Observation
@@ -18,13 +19,15 @@
   deriving (Show, Eq)
 
 -- | Status of a connection.
+--
+-- <<diagrams-output/observation-status-model.png>>
 data ConnectionStatus
   = -- | Connection is being established.
     --
     -- This is the initial status of every connection.
     ConnectingConnectionStatus
   | -- | Connection is established and not occupied.
-    ReadyForUseConnectionStatus
+    ReadyForUseConnectionStatus ConnectionReadyForUseReason
   | -- | Is being used by some session.
     --
     -- After it's done the status will transition to 'ReadyForUseConnectionStatus' or 'TerminatedConnectionStatus'.
@@ -33,6 +36,15 @@
     TerminatedConnectionStatus ConnectionTerminationReason
   deriving (Show, Eq)
 
+data ConnectionReadyForUseReason
+  = -- | Connection just got established.
+    EstablishedConnectionReadyForUseReason
+  | -- | Session execution ended with a failure that does not require a connection reset.
+    SessionFailedConnectionReadyForUseReason Session.QueryError
+  | -- | Session execution ended with success.
+    SessionSucceededConnectionReadyForUseReason
+  deriving (Show, Eq)
+
 -- | Explanation of why a connection was terminated.
 data ConnectionTerminationReason
   = -- | The age timeout of the connection has passed.
@@ -43,4 +55,6 @@
     NetworkErrorConnectionTerminationReason (Maybe Text)
   | -- | User has invoked the 'Hasql.Pool.release' procedure.
     ReleaseConnectionTerminationReason
+  | -- | Initialization session failure.
+    InitializationErrorTerminationReason Session.QueryError
   deriving (Show, Eq)
diff --git a/src/library/other/Hasql/Pool/Config/Config.hs b/src/library/other/Hasql/Pool/Config/Config.hs
--- a/src/library/other/Hasql/Pool/Config/Config.hs
+++ b/src/library/other/Hasql/Pool/Config/Config.hs
@@ -4,6 +4,7 @@
 import qualified Hasql.Pool.Config.Defaults as Defaults
 import Hasql.Pool.Observation (Observation)
 import Hasql.Pool.Prelude
+import qualified Hasql.Session as Session
 
 -- | Configufation for Hasql connection pool.
 data Config = Config
@@ -12,7 +13,8 @@
     agingTimeout :: DiffTime,
     idlenessTimeout :: DiffTime,
     connectionSettingsProvider :: IO Connection.Settings,
-    observationHandler :: Observation -> IO ()
+    observationHandler :: Observation -> IO (),
+    initSession :: Session.Session ()
   }
 
 -- | Reasonable defaults, which can be built upon.
@@ -24,5 +26,6 @@
       agingTimeout = Defaults.agingTimeout,
       idlenessTimeout = Defaults.idlenessTimeout,
       connectionSettingsProvider = Defaults.dynamicConnectionSettings,
-      observationHandler = Defaults.observationHandler
+      observationHandler = Defaults.observationHandler,
+      initSession = Defaults.initSession
     }
diff --git a/src/library/other/Hasql/Pool/Config/Setting.hs b/src/library/other/Hasql/Pool/Config/Setting.hs
--- a/src/library/other/Hasql/Pool/Config/Setting.hs
+++ b/src/library/other/Hasql/Pool/Config/Setting.hs
@@ -5,6 +5,7 @@
 import qualified Hasql.Pool.Config.Config as Config
 import Hasql.Pool.Observation (Observation)
 import Hasql.Pool.Prelude
+import qualified Hasql.Session as Session
 
 apply :: Setting -> Config -> Config
 apply (Setting run) = run
@@ -86,3 +87,11 @@
 observationHandler :: (Observation -> IO ()) -> Setting
 observationHandler x =
   Setting (\config -> config {Config.observationHandler = x})
+
+-- | Initial session.
+--
+-- Gets executed on every connection upon acquisition.
+-- Lets you specify the connection-wide settings.
+initSession :: Session.Session () -> Setting
+initSession x =
+  Setting (\config -> config {Config.initSession = x})