This chapter presents an introduction to advanced gold standard accountability procedures for athlete assessment and intervention. The best way to demonstrate the validity of an assessment battery or efficacy of an intervention is through an accountability process. Relative to athlete assessment, accountability can and should be demonstrated in the construct validity of a specific psychological, behavioral, or psychophysiological measure that is being assessed. The field of applied sport psychology is replete with research-based systems, eclectic and hybrid athlete evaluation, and mental training methods, as well as extreme Guru-propagated, “analyze and cure-all” schemes that promise or guarantee incredible success. The preceding data set is consistent with individual athlete differential mind-body responses that have been observed in extensive previous intervention efficacy research. Practitioners should generate and maintain an accountability database throughout the course of their work with an athlete.