Working across knowledge-based research programmes, rather than institutional structures, should be central to interdisciplinary research. In this paper, a novel framework is proposed to facilitate interdisciplinary research, with the goals of promoting communication, understanding and collaborative work. Three core elements need to be addressed to improve interdisciplinary research: the types (forms and functions) of theories, the underlying philosophies of knowledge and the combination of research styles; these three elements combine to form the research programme. Case studies from sustainability science and environmental security illustrate the application of this research programmebased framework. This framework may be helpful in overcoming often oversimplified distinctions, such as qualitative/quantitative, deductive/inductive, normative/descriptive, subjective/objective and theory/practice. Applying this conceptual framework to interdisciplinary research should foster theoretical advances, more effective communication and better problem-solving in increasingly interdisciplinary environmental fields.