Well-being is the ultimate goal of social protection that integrates both material and social aspects. Most studies focus on material dimensions, and little attention has been given to the social aspects of well-being. Further, outputs are commonly used to assess the effectiveness of social protection, while insufficient attention has been given to the outcomes and process evaluation. This study aims to assess the effectiveness of social protection in ensuring well-being, comprising human development and social cohesion. It adopts a result-oriented framework that considers both outcome and process evaluation. The study follows sequential mixed methods for assessing the effectiveness of social protection programmes. Using a secondary dataset of six developing countries (including Bangladesh) from 2002 to 2019 and employing a pooled OLS model, this study shows that social protection expenditure increases the primary (education) completion rate and reduces the child (under 5) mortality rate in developing countries. It also reveals that the effect of social protection on education and health outcomes improves with governance efficacy and operational competency. Using primary data collected through a quantitative survey (n=400) from four districts of Bangladesh and employing the OLR model, this study shows that social protection benefits positively affect informal and formal networks and institutional trust and norms of behaviour. It also reveals that the educational status of beneficiaries can mediate informal and formal networks, interpersonal trust, and norms of reciprocity. The process evaluation has done through 24 in-depth qualitative interviews with key stakeholders. By using content analysis, this study recognises five "governance" and six "operational" issues that can limit the effectiveness of social protection programmes. It also proposes a model for the effective functioning of social protection programmes based on empirical findings and justified by prevailing literature. The study shows how effectively programmes are executed and how programmes can be improved to achieve the goal. These findings have significant implications for enhancing the development effectiveness of social protection programmes. The policy directions can assist policymakers and development partners in taking suitable policies to ensure the well-being of the poor and vulnerable people of developing countries. / Government of the People's Republic of Bangladesh research grants, National Academy for Planning and Development (NAPD)