Individual therapy and group therapy are economically sensible. Group therapy is suitable for disorders that are very common. Three good reasons to offer sigmatism therapy in groups: Karen Grosstück has developed and evaluated a proven therapy program over more than 18 years. The most important result is that the program, with its 14 therapy units, is sufficient to eliminate isolated sigmatism in 88% of all cases. The book presents the results and the program with practical instructions for its implementation and aims to encourage the offering of more group therapy in speech therapy.