diff --git a/P3/P3Client.class.st b/P3/P3Client.class.st
index 4e45b68..f88e5fd 100644
--- a/P3/P3Client.class.st
+++ b/P3/P3Client.class.st
@@ -81,7 +81,8 @@ Class {
 		'settings',
 		'properties',
 		'converter',
-		'message'
+		'message',
+		'access'
 	],
 	#category : #'P3-Core'
 }
@@ -114,6 +115,13 @@ P3Client >> authenticationTypes [
 		10 -> #SASL } asDictionary
 ]
 
+{ #category : #'initialize-release' }
+P3Client >> beThreadSafe [
+	"Configure me so that I can be safely used from multiple threads/processes during important operations"
+	
+	access := Monitor new
+]
+
 { #category : #private }
 P3Client >> clearSSL [
 	settings removeKey: #ssl ifAbsent: [ ]
@@ -148,12 +156,13 @@ P3Client >> close [
 P3Client >> connect [
 	"Connect me to a PostgreSQL database. 
 	Run the authentication and startup protocols. Configure the session."
-	
-	self 
-		ensureOpen;
-		connectInternal;
-	 	clearSSL;
-		logConnected
+
+	self critical: [ 
+		self
+			ensureOpen;
+			connectInternal;
+			clearSSL;
+			logConnected ]
 ]
 
 { #category : #protocol }
@@ -172,14 +181,14 @@ P3Client >> connectInternal [
 P3Client >> connectSSL [
 	"Connect me to a PostgreSQL database over an encrypted SSL connection. 
 	Run the authentication and startup protocols. Configure the session."
-	
-	self 
-		ensureOpen;
-	 	upgradeToSSL;
-		connectInternal;
-	 	setSSL;
-		logConnected 
 
+	self critical: [
+		self
+			ensureOpen;
+			upgradeToSSL;
+			connectInternal;
+			setSSL;
+			logConnected ]
 ]
 
 { #category : #accessing }
@@ -216,6 +225,13 @@ P3Client >> createPreparedStatementNamed: name withParameters: parameterDescript
 	^ preparedStatement
 ]
 
+{ #category : #private }
+P3Client >> critical: block [
+	^ access
+		ifNil: block
+		ifNotNil: [ access critical: block ]
+]
+
 { #category : #accessing }
 P3Client >> database [
 	"Return the database name I (want to) connect to.
@@ -374,6 +390,8 @@ P3Client >> initialize [
 	
 	settings := IdentityDictionary new.
 	properties := Dictionary new.
+	
+	self beThreadSafe
 ]
 
 { #category : #private }
@@ -646,41 +664,40 @@ P3Client >> prepare: query named: queryName [
 
 	| parameterDescriptions rowDescriptions statement |
 
-	self 
-		ensureConnected;
-		writeParseMessage: query name: queryName types: #();
-		writeDescribeMessage: queryName type: $S;
-		writeSyncMessage.
+	self critical: [
+		self 
+			ensureConnected;
+			writeParseMessage: query name: queryName types: #();
+			writeDescribeMessage: queryName type: $S;
+			writeSyncMessage.
 
-	self readMessage tag = $1
-		ifFalse: [ ^ P3Error parseCompleteExpected signal ].
+		self readMessage tag = $1
+			ifFalse: [ ^ P3Error parseCompleteExpected signal ].
 
-	self readMessage.
-	message tag = $t
-		ifTrue: [ parameterDescriptions := self processParameterDescription: message readStream ]
-		ifFalse: [ 
-			parameterDescriptions := #().
-			message tag = $n 
-				ifFalse: [ P3Error noDataExpected signal ] ].
+		self readMessage tag = $t
+			ifTrue: [ parameterDescriptions := self processParameterDescription: message readStream ]
+			ifFalse: [ 
+				parameterDescriptions := #().
+				message tag = $n 
+					ifFalse: [ P3Error noDataExpected signal ] ].
 
-	self readMessage.
-	message tag = $T
-		ifTrue: [ rowDescriptions := self processRowDescription: message readStream ]
-		ifFalse: [ 
-			rowDescriptions := #().
-			message tag = $n
-				ifFalse: [ P3Error noDataExpected signal ] ].
+		self readMessage tag = $T
+			ifTrue: [ rowDescriptions := self processRowDescription: message readStream ]
+			ifFalse: [ 
+				rowDescriptions := #().
+				message tag = $n
+					ifFalse: [ P3Error noDataExpected signal ] ].
 
-	self readMessage tag = $Z
-		ifFalse: [ ^ P3Error readyForQueryExpected signal ].
+		self readMessage tag = $Z
+			ifFalse: [ ^ P3Error readyForQueryExpected signal ].
 
-	statement := self 
-		createPreparedStatementNamed: queryName 
-		withParameters: parameterDescriptions 
-		andFields: rowDescriptions.
+		statement := self 
+			createPreparedStatementNamed: queryName 
+			withParameters: parameterDescriptions 
+			andFields: rowDescriptions.
 	
-	self logPreparedStatement: statement query: query.
-	 	
+		self logPreparedStatement: statement query: query ].
+
 	^ statement
 ]
 
@@ -775,11 +792,12 @@ P3Client >> query: query [
 	Descriptions is a collection of row field description objects, if any.
 	Data is a collection of rows with fully converted field values as objects, if any."
 
-	^ self withConnection: [
-		self 
-			ensureConnected;
-			writeQueryMessage: query;
-			runQueryResult ]
+	^ self critical: [
+		self withConnection: [
+			self 
+				ensureConnected;
+				writeQueryMessage: query;
+				runQueryResult ] ]
 ]
 
 { #category : #accessing }
@@ -901,13 +919,15 @@ P3Client >> runExtendedQueryResults: fieldDescriptions [
 	
 	| results queryStarted |
 
-	queryStarted := Time millisecondClockValue.
-	self readMessage.
-	results := Array streamContents: [ :out |
-		[
-			properties at: #query_started ifAbsentPut: queryStarted. "each result will use the same start"
-			out nextPut: (self runExtendedQueryResult: fieldDescriptions).
-			self readMessage tag = $Z ] whileFalse ].
+	self critical: [
+		queryStarted := Time millisecondClockValue.
+		self readMessage.
+		results := Array streamContents: [ :out |
+			[
+				"each result will use the same start"
+				properties at: #query_started ifAbsentPut: queryStarted.
+				out nextPut: (self runExtendedQueryResult: fieldDescriptions).
+				self readMessage tag = $Z ] whileFalse ] ].
 	
 	^ results
 ]