Evidence based or empirically supported psychotherapies are becoming more and more important in the mental health fields as the users and financers of psychotherapies want to choose those methods whose effectiveness are empirically shown. Cognitive-behavioral psychotherapies are shown to have empirical support in the treatment of a wide range of psychological/psychiatric problems. As a cognitive-behavioral mode of action, Problem Solving Therapy has been shown to be an effective psychotherapy approach in the treatment and/or rehabilitation of persons with depression, anxiety, suicide, schizophrenia, personality disorders, marital problems, cancer, diabetes-mellitus etc. Mental health problems cause personal suffering and constitue a burden to the national health systems. Scientific evidence show that effective problem solving skills are an important source of resiliency and individuals with psychological problems exhibit a deficiency in effective problem solving skills. Problem solving therapy approach to the treatment and/or rehabilitation of emotional problems assumes that teaching effective problem solving skills in a therapeutic relationship increases resiliency and alleviates psychological problems.The book, in the first chapters, gives information on problem solving and the role of problem-solving in the etiology and the treatment of different forms of mental health problems. In the later chapters, it concentrates on psychotherapy, assessment and procedures of problem solving therapy. At the end it provides a case study.