The different schools of family therapy have in common a belief that, regardless of the origin of the problem, and regardless of whether the clients consider it an "individual" or "family" issue, involving families in solutions often benefits clients. This involvement of families is commonly accomplished by their direct participation in the therapy session. The skills of the family therapist thus include the ability to influence conversations in a way that catalyses the strengths, wisdom, and support of the wider system.
In the field's early years, many clinicians defined the family in a narrow, traditional manner usually including parents and children. As the field has evolved, the concept of the family is more commonly defined in terms of strongly supportive, long-term roles and relationships between people who may or may not be related by blood or marriage.