This paper discusses the notion of naturalism in relation to intentionality. Intentionality is considered "the mark of the mental", and its reduction to physiology is a crucial issue for theoretical psychology. Naturalism seems to entail reductionism: it is usually identified with exclusive adherence to a physical level of description and a reductionist view on mentality. However, it is argued that naturalism can also be construed in a more biological way, as an evolutionary, functionalist, non-reductionist view of mind. Such a functionalist view emphasizes the role of mind in the adaptation of the organism to the environment. The computational approach to mind, which attempts to reconcile mentalism with scientific rigor, is discussed as a form of syntactic reductionism. A naturalist, non-reductionist conception of intentionality is sketched, which views mind as organism-environment relation and draws upon Searle's biologically oriented conception of intentionality and on Gibson's account of perception as reciprocity of organism and environment.