Evolutionary and environmental theories of erotic response, sometimes termed“sociobiology”and“socialization”theories, respectively, are compared on the basis of the structural strengths and weaknesses of each approach. More space is devoted to the evolutionary approach because sociobiologists have offered a more detailed theoretical analysis, thereby allowing for greater criticism and, also, because these theories are not directly testable. Examination of socialization theories is more straightforward. The review focuses on how the presence of an effect favors either an environmental or an evolutionary interpretation. This review is concerned with the basic methodology and the sharpening of theoretical concepts which may be used to develop more complex accounts of erotic response. The term“erotic response”refers to sexual arousal and/or attraction. A sequel to this article will examine the utility of these approaches within specific content domains