The purpose of this Delphi study was to explore and identify a panel of experts' opinions of essential elements for successful multi-family group therapy (MFGT) and to propose the identified elements as guidelines for future MFGT theoretical and program development. Multi-family group therapy continues to be implemented while there is little empirical research to support how it is effective and with what populations and presenting problems it is best employed. A panel of MFGT experts identified 35 essential elements for successful MFGT. Many of the identified elements coincided with elements identified in the relevant literature. However, elements specific to MFGT were distinguished. The essential elements are presented as guidelines for MFGT theoretical and program development. The implications of this study for theory, research, and practice are discussed. / Ph. D.