Countries enact healthcare reforms for integrated care services. Evaluating their impact and setting performance indicators is crucial yet challenging. This chapter outlines principles for evaluation. Designs must define goals, identify value-creating mechanisms, select indicators, and aid improvement plans. Integrated services aim for the “triple aim”: better population health, patient/carer experience, and cost reduction. Evaluators must also consider structural factors like political support, governance, and value creation mechanisms, such as health intelligence and system coordination. Contextual factors like population size and initiative scale matter too. Various data sources are needed, but challenges include complexity and limited trial designs. Drawing from experience, this chapter offers insights for assessing integrated care system performance, aiding healthcare stakeholders.