Psychology 

Motivation 

• Why We Do What We Do by Edward Deci
• Punished by Rewards by Alfie Kohn 

Positive Psychology 

• Authentic Happiness by Martin Seligman
• Learned Optimism by Martin Seligman
• Stumbling on Happiness by Daniel Gilbert
• How We Choose To Be Happy by Rick Foster and Greg Hicks
• Satisfaction: The Science of True Fulfillment by Gregory Burns
• The Pursuit of Happiness: Who is Happy--And Why by David G. Myers
• The Science of Happiness by Stefan Klein, Ph.D.
• Happiness - Lessons From a New Science by Richard Layard
• The Happiness Hypothesis by Jonathan Haidt
• The How of Happiness by Sonja Lyubomirsky
• Spiritual Evolution by George Vaillant
• Creating Your Best Life by Caroline Adams Miller and Michael B. Frisch

Relationships 

• Why Men Marry Some Women And Not Others by John T. Molloy

Social Psychology

• Yes! by Robert Cialdini
• Predictably Irrational by Dan Ariely

Evolutionary Psychology

• Why Beautiful People Have More Daughters by Alan Miller and Satoshi Kanazawa