Given the challenges of food security and environmental degradation, sustainable intensification (SI) that combines food production and environmental goals has received growing attention. This study traces the heterogeneous debate in a systematic literature review covering 20 years. To enhance structured, action-oriented understanding, we propose a conceptual framework that anchors the portfolio of SI practices in four fields of action covering farm to landscape level and land-use to organisational optimisation. Applying the framework in four European case studies demonstrates that future research and context-specific implementation must focus on the decision-making rationales of agents, coordinated action and coupling of locally-adapted practices.