The degree to which fatty acids modulate brain function beyond periods of rapid brain growth is poorly understood. Nevertheless, recent evidence suggests that dietary fatty acid composition influences numerous behaviors including body temperature regulation, pain sensitivity, feeding behavior including macronutrient selection, and cognitive performance. Importantly, alterations are observed in the absence of essential fatty acid (EFA) deficiency, beyond periods of rapid brain development, and at levels similar to those consumed by the North American population. Data suggest that the content of saturated fatty acids (SFAs), and not that of the EFAs, may be the important component of dietary fat mediating macronutrient selection and cognition under these experimental conditions. Yet, a direct role of SFAs in modulating brain functions has not been elucidated. A discussion of potential mechanisms which may directly involve the central nervous system, or may indirectly influence central processes via peripheral pathway(s) is presented.