The traditional top-down approach to program outcome evaluation stresses the need for strong evidence to establish an intervention's effectuality. This approach's principles and methodology are rooted in Campbellian typology and have been applied intensively in outcome evaluation. Yet lessons learned from such applications suggest that in addressing stakeholders' interests and needs, this approach has limitations. To be stakeholder responsive, evaluation must go beyond the top-down approach's focus and strategies. This chapter proposes an integrative validity model and a bottom-up approach as an alternative perspective to outcome evaluation. The new perspective enables evaluations to meet both scientific and practical requirements and enhances evaluations' usefulness. © Wiley Periodicals, Inc., and the American Evaluation Association.1