 Although often grouped together, monitoring and evaluation are two distinct but related functions. Monitoring involves overseeing the progress of a program operationally and financially. Evaluating entails systematically and objectively assessing an ongoing or completed program or project, its design, implementation and results. M&E is a crucial component of return and reintegration programs to assess their performance and whether they meet their intended objectives. What does sustainability look like in return and reintegration programs? How can we ensure transparency and accountability for the beneficiaries? Two questions M&E can address. To this end, IOM standardised the measurements of reintegration sustainability, which led to the development of the Reintegration Sustainability Survey, a self-assessment questionnaire completed by the returnee. The RSS generates a composite reintegration and three-dimensional scores. The foremost indicates overall reintegration sustainability, while the latter measures sustainability in reintegration's economic, social and psychosocial dimensions. Two migrants with a similar composite reintegration score can have very different dimensional scores, reintegration experiences and needs. The economic indicators gather info on income sources, employment, indebtedness, food security and an assessment of the returnee's financial situation. The social indicators are about access to essential services such as housing, education, justice and healthcare. The psychosocial indicators offer insights into the sense of belonging, participation in social activities, the ability to rely on a support network and potential tensions and conflicts. The RSS is part of a comprehensive M&E package for reintegration practitioners. Developed by the EU IOM Knowledge Management Hub, it consists of survey templates, a results monitoring framework and guidance material. Surveys target programmes beneficiaries, community members and other key stakeholders involved in return and reintegration. Data gathered through the RSS and other M&E tools feed into IOM's research and studies. These tools and guidance are available on IOM's return and reintegration platform. Check them out today.