Tara, a professional woman, artist, wife and mother, diagnosed with Dissociative Identity Disorder (formerly referred to as MPD - Multiple Personality Disorder) stops taking her medication and struggles to unite her "alters" (alternate personalities.) As the seemingly disparate portions of her psyche seek to combine and peaceably co-exist, Tara, her husband, their kids, family and friends deal with the fallout, life and various morons who do not know their schizophrenia from their MPD. Written by LA-Lawyer
I also don't understand the negative comments about this show, for example the fact that drugs and alcohol are present. This is what makes the show realistic (except perhaps for a subsection of the population who don't accept that alcohol and drugs are part of North American society). The characters are believable and sometimes quite funny. Some of the episodes, for example the one in which Tara's sister undergoes a second breast operation, push American obsession with perfect beauty to the limit. As others have said, Collette is outstanding as Tara but the other actors more than hold their own next to her various roles. This is a very idiosyncratic take on contemporary society.