This book explains the process of intervention set selection and provides guidance for anyone seeking to improve performance. The 15 principles generated serve as a guide professionals can use to select an intervention set. The principles explain how and why certain actions happen during the intervention set selection phase and they function as a guide for practitioners when selecting intervention sets. A schemata, that consists of composition, directional dependence, mechanism of action, enforcement, transformation, and reverberation adds to the field of performance improvement. Identifying these factors explains a practitioner's behaviors when selecting an intervention set. The schemata also illustrate the art and science inherent in intervention set selection. The value of a "set" is to create the most comprehensive intervention to assure successful human performance. The book concludes by encouraging others to continue the journey.