Can anyone recommend a good child psychology book?

I think it's awesome to be proactive and to feel prepared (although you'll find if you have children nothing can completely prepare you). I highly recommend the Babywise series by Ezzo. I love his principles (not used in the extreme, of course). It's mainly based around sleeping & eating cycles, but when utilized correctly, result in a very content, alert, and well rested baby. It also discusses the baby's place in the family unit etc. Very useful tool to everyone I know that's used it. Hope that helps. Good luck.