Tom Douglas 
Theory of Groupwork Practice [PDF ebook] 

A Theory of Groupwork Practice is based on the results of the search for the fundamental similarities in the practice of all groupworkers in whatever profession or setting they may operate. The theoretical concepts used by groupworkers may be widely variant, but what workers actually do when in interaction with the groups they create or adapt shows remarkable similarities which are deeper and more influential than the concepts in promoting or preventing successful group outcomes. This book presents the foundations of a coherent theory of group work practice based on these similarities.