This study investigated gender differences in North American preschoolers' biological reasoning about the concept of "life". Four-year-olds (M = 4.6, SD = 3.3 months) and five-year-olds (M = 5.6, SD = 3.8 months) were asked about the function of 13 body parts, organs, and bodily processes. Results indicated that the likelihood of mentioning the importance of body parts, organs, and bodily processes for maintaining life or preventing death was predicted by age. A concept of life was more likely to occur in boys rather than girls. Although boys had a greater understanding of life they did not outperform girls in their responses to organ/ body part function. The results demonstrate that gender differences in biological reasoning emerge during the preschool years. Implications for early science education are discussed. (Contains 3 tables.)