You don't mention which model of MacBook you have. The last MacBook produced was the mid 2010 model. Apple says it could take 4GB of RAM but other users have reported being able to use up to 16GB.
You can use this Apple article to find out which model MacBook you have.
After determining the model you can search for that model's specifications for the max amount of RAM.
Best of luck.
Have a look at OWC's site for your model - http://eshop.macsales.com/shop/memory/Apple_MacBook_MacBook_Pro/Upgrade/Macbook_ selector
OWC lists what they themselves have tested and verified as stable and useable in those models.