This study explored differences in children’s perceptions of war among three age groups. A qualitative research design was adopted. In-depth interviews were conducted with a total of 50 children recruited from two mid-western university towns in the U.S. Comparisons of perception differences also were made between Taiwanese American (TA) children and non-Taiwanese American (NTA) children on the basis of different age groups. Age was found to be an important factor influencing children’s perceptions of war. In general, children in the youngest age group described war mainly in terms of war activities and weapons. Those in the middle and oldest age groups were much more likely than the youngest children to include consequences and causes of war in their descriptions. Individual differences also were discussed. The results of this study indicated a strong similarity between TA and NTA children’s descriptions of war; however, a few differences also were identified, some of which seemed to be related to TA children’s unique cultural background. Piaget’s cognitive development theory and Symbolic Interactionism were adopted to explain and understand the differences found in age groups and ethnic groups. Implications for practice and future research are suggested.