This introduction provides a brief sketch of explanatory pluralism and related issues. It is argued that traditional ideas in the philosophy of science about connections between levels of explanation, autonomy and reduction are too simple to account for the multifaceted explanatory relations between psychology and its neighboring disciplines. Explanatory pluralism holds that theories at different levels can co-evolve and mutually influence each other, without reduction of the higher-level theory to the lower-level one. Establishing bridges between cognitive psychological and neuro-physiological theories may suggest problems and solutions, and thus foster further development, both ways. The ideas put forward in this Symposium provide resources for a pluralistic view on psychological explanation, and militate against the ‘single-plot story’ that physiological reductionism holds up as an ideal to psychology. © 2001, Sage Publications. All rights reserved.