Community-based sustainability initiatives have emerged as pivotal mechanisms for addressing environmental challenges while generating measurable returns on investment (ROI) across corporate and public sectors. This study examines the effectiveness of community engagement models, comparing corporate approaches exemplified by companies like Starbucks with public sector methodologies for evaluating localized green initiatives. Through comprehensive analysis of cost-benefit frameworks, Social Return on Investment (SROI) methodologies, and community participatory evaluation models, this research reveals significant disparities in ROI measurement approaches and outcomes between sectors. The findings demonstrate that while corporate initiatives often prioritize brand value and stakeholder engagement metrics, public sector programs emphasize long-term community resilience and environmental impact. This comparative analysis provides a framework for optimizing sustainability investments through enhanced community engagement strategies and standardized evaluation methodologies.