The twenty-first century presents social work with significant challenges. To address today s complex problems, social work must inform itself of advances in the knowledge base of the natural and social sciences, particularly those that explain the changing construction of different systems and the way the world works. These explanatory theories offer relevant understanding of the social, economic and ecological contexts within which social workers practice.We discuss social work s search for coherence and the consequences that arise when a profession seeks to explain the way the world works through practice perspectives. We examine developments in the natural and social sciences that offer social work pathways to understanding the contemporary world. Complexity theory and evolutionary theory are essential to understanding the dynamics and causation of contemporary problems. Neuroscience, evolutionary theory and complexity theory provide social work with a new understanding of the relationship between people, their bodies and environments. Social workers focus should be on working at the borders of evolving systems, effecting the climates that can sustain those conditions (social, ecological, biological, economic, political) essential to maintaining human life and well-being. A? The Author 2010.