While considerable research explores the phenomenon of early-career teacher retention, surprisingly few studies report long-term intervention strategies that attempt to resolve this issue. For context, the paper briefly describes one exception, a seven-year longitudinal project involving over 170 secondary teachers that provides mechanisms to help teachers remain positively active in the workforce. It focuses specifically on an issue that potentially hinders the full impact of such intervention studies -- developing a robust instrument capable of measuring teacher retention interventions over time. This paper specifically reports on the exploratory and confirmatory factor analyses conducted to validate the TAP tool.