Marsha Linehan (1991) pioneered this treatment, based on the idea that psychosocial treatment of those with Borderline Personality Disorder was as important in controlling the condition as traditional counseling and pharmacotherapy were. In conjunction with this belief was a hierarchical structure of treatment goals. Paramount among these was reducing parasuicidal (self-injuring) and life-threatening behaviors. Next came reducing behaviors that interfered the therapy/treatment process, and finally reducing behaviors that reduced the client's quality of life. Various studies have shown DBT to be effective in treating a variety of symptoms. The following link is a summary of studies done to date:
Basically, DBT maintains that some people, due to invalidating environments during upbringing and due to biological factors as yet unknown, react abnormally to emotional stimulation. Their level of arousal goes up much more quickly, peaks at a higher level, and takes more time to return to baseline. This explains why people suffering from symptoms of Borderline Personality Disorder are known for crisis-strewn lives and extreme emotional lability (emotions that shift rapidly). Because of their past invalidation, they don't have any methods for coping with these sudden, intense surges of emotion. DBT is a method for teaching skills that will help in this task.