The purpose of this special series is to highlight how the measurement of integrity, both treatment integrity and integrity for implementation strategies, can support intervention development, evaluation, and implementation research. The seven papers and one commentary in this special series illustrate how diverse measurement approaches are used for integrity across various types of intervention research. This introductory paper provides a general overview of the themes that cut across the papers in this special series. We define key terms and discuss how the measurement of treatment integrity (i.e., extent to which the core practices of a protocol are delivered) and integrity to implementation strategies (i.e., extent to which the core practices of an implementation strategy are delivered) changes as an intervention progresses along the treatment development pipeline spanning from basic research to implementation and dissemination research. Then we discuss the ways that the measurement of integrity can change across the different steps in the pipeline to meet the goals associated with different stops along the pipeline. We finish the paper with a description of the papers in the special series and concluding thoughts. [This article was published in "School Mental Health" (EJ1328192).]