diff --git a/pom.xml b/pom.xml
index f7f2d85..de55bba 100644
--- a/pom.xml
+++ b/pom.xml
@@ -43,11 +43,22 @@
     </distributionManagement>
 
     <dependencies>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.9</version>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
             <version>[2.5.0,2.5.1]</version>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.9</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
diff --git a/src/main/java/com/force/api/ForceApi.java b/src/main/java/com/force/api/ForceApi.java
index b83d969..0caef6f 100644
--- a/src/main/java/com/force/api/ForceApi.java
+++ b/src/main/java/com/force/api/ForceApi.java
@@ -10,9 +10,10 @@
 import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 import com.fasterxml.jackson.databind.node.JsonNodeFactory;
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
@@ -42,6 +43,8 @@ public class ForceApi {
 
 	private static final ObjectMapper jsonMapper;
 
+	private static final Logger logger = LoggerFactory.getLogger(ForceApi.class);
+
 	static {
 		jsonMapper = new ObjectMapper();
 		jsonMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
@@ -180,8 +183,8 @@ public CreateOrUpdateResult createOrUpdateSObject(String type, String externalId
 			} else if(res.getResponseCode()==204) {
 				return CreateOrUpdateResult.UPDATED;
 			} else {
-				System.out.println("Code: "+res.getResponseCode());
-				System.out.println("Message: "+res.getString());
+				logger.debug("Code: {}",res.getResponseCode());
+				logger.debug("Message: {}",res.getString());
 				throw new RuntimeException();
 			}
 
@@ -315,8 +318,8 @@ private final HttpResponse apiRequest(HttpRequest req) {
 		HttpResponse res = Http.send(req);
 		if(res.getResponseCode()==401) {
 			// Perform one attempt to auto renew session if possible
-			if(autoRenew) {
-				System.out.println("Session expired. Refreshing session...");
+			if (autoRenew) {
+				logger.debug("Session expired. Refreshing session...");
 				if(session.getRefreshToken()!=null) {
 					session = Auth.refreshOauthTokenFlow(config, session.getRefreshToken());
 				} else {
@@ -334,7 +337,7 @@ private final HttpResponse apiRequest(HttpRequest req) {
 			}
 		} else if(req.getExpectedCode()!=-1 && res.getResponseCode()!=req.getExpectedCode()) {
 			throw new RuntimeException("Unexpected response from Force API. Got response code "+res.getResponseCode()+
-					". Was expecing "+req.getExpectedCode());
+					". Was expecting "+req.getExpectedCode());
 		} else {
 			return res;
 		}
@@ -342,8 +345,8 @@ private final HttpResponse apiRequest(HttpRequest req) {
 	
 	/**
 	 * Normalizes the JSON response in case it contains responses from
-	 * Relationsip queries. For e.g.
-	 * 
+	 * relationship queries. For e.g.
+	 *
 	 * <code>
 	 * Query:
 	 *   select Id,Name,(select Id,Email,FirstName from Contacts) from Account
diff --git a/src/main/java/com/force/api/http/Http.java b/src/main/java/com/force/api/http/Http.java
index d717e7c..afa5e32 100644
--- a/src/main/java/com/force/api/http/Http.java
+++ b/src/main/java/com/force/api/http/Http.java
@@ -1,5 +1,8 @@
 package com.force.api.http;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
@@ -11,6 +14,8 @@
 
 
 public class Http {
+
+	static final Logger logger = LoggerFactory.getLogger(Http.class);
 	
 	static final byte[] readResponse(InputStream stream) throws IOException {
 		BufferedInputStream bin = new BufferedInputStream(stream);
@@ -63,7 +68,7 @@ public static final HttpResponse send(HttpRequest req) {
 					return new HttpResponse().setStream(conn.getInputStream()).setResponseCode(code);
 				}
 			} else {
-				System.out.println("Bad response code: " + code + " on request:\n" + req);
+				logger.info("Bad response code: {} on request: {}", code, req);
 				HttpResponse r = new HttpResponse().setString(
 						new String(readResponse(conn.getErrorStream()), "UTF-8")).setResponseCode(code);
 				return r;
diff --git a/src/test/java/com/force/api/EndToEndOAuthFlowExample.java b/src/test/java/com/force/api/EndToEndOAuthFlowExample.java
index 3a56323..0f0469c 100644
--- a/src/test/java/com/force/api/EndToEndOAuthFlowExample.java
+++ b/src/test/java/com/force/api/EndToEndOAuthFlowExample.java
@@ -45,7 +45,7 @@ public void endToEndOAuthFlowTest() throws FailingHttpStatusCodeException, Malfo
 
         // --------------------------------------------------------------------
         // This part is what you'd normally do somewhere in your web app when
-        // you want to authenticate an unauthenticate user.
+        // you want to authenticate an unauthenticated user.
 
         ApiConfig config = new ApiConfig().setClientId(Fixture.get("clientId"))
                 .setClientSecret(Fixture.get("clientSecret")).setRedirectURI(Fixture.get("redirectURI"));