Since James, some psychologists have referred to evolutionary theory as one of the sources of explaining behavior (James, 1890). However, the status of such references is not always clear. In the recent work of many authors,(1) it is not always clear (1) what kind of causal analyses are appropriate in psychology beyond those psychologists already use; (2) how psychological explanations fit in the general scheme of explanations in the life sciences, especially in biological explanatory schemes; and (3) what this implies for the evaluation of available evidence. This chapter is about these questions. I discuss five types of explanations involved in psychological explanations using an evolutionary perspective, and I discuss how these types of analysis relate to types of propositions and types of evidence.