This paper, facilitated by FARA, is intended to contribute towards an understanding of ‘Integrated Agricultural Research for Development’ (IAR4D). The authors first review four ‘defining principles’ of IAR4D, the theories and experiences that have contributed to the formulation of these principles, and actions that can contribute to putting these principles into practice. The paper then summarizes the individual, organizational and institutional capacity that is needed to create the enabling environment for IAR4D.