Knowledge tests used to evaluate child protection training program effectiveness for early childhood education providers may suffer from threats to construct validity given the contextual variability inherent within state-specific regulations around mandated reporting requirements. Unfortunately, guidance on instrument revision that accounts for such state-specific mandated reporting requirements is lacking across research on evaluation practices. This study, therefore, explored how collection and integration of validity evidence using a mixed methods framework can guide the instrument revision process to arrive at a more valid program outcome measure.