One of the best books I've read on the issues with developing and maintaining an effective team is the book, "The Five Dysfunctions of a Team", authored by Patrick Lencioni. This book using a fable illustrates the importance of the psychological issues that can seriuosly affect team effectiveness. This is good reading for any organization wishing to improve team work. 

My experience suggests that trust (or lack thereof) is the biggest single issue facing teams. Many people feel accountability is the biggest issue. I feel accountability and responsibility flows from trust. If trust is missing most people will not accept accountability for their or team mates' actions. Please let me know what you think.