This thesis compared the nature of friendship among American and Japanese college students of both sexes. The process of making and keeping friends, the characteristics of friendship, and the potential causes of the break-up of friendship were explored with a 75-item, paper-and-pencil questionnaire. The respondents were fellow college students at Waseda University in Tokyo while I was studying there during 2012-13, numbering 32 Japanese (18 women and 14 men) and 32 Americans (17 women and 15 men). The research questions were: (1) Within a given culture, either American or Japanese, are there differences between men and women in their friendship dynamics? (2) Are there any cultural contrasts in the nature of friendship between Americans and Japanese? and (3) If there are indeed some differences of either variety, what is the nature of the disparities? In total, 14 statistically significant results were discovered: six divergences between the two sexes (three each for the two groups, Americans and Japanese) and eight cultural contrasts. Attentiveness, placidity, and attractiveness were at issue between the American men and women, while togetherness, serious conversation, and the scope of social connections were dividing factors for the Japanese. The cultural contrasts consisted of the ways of finding a friend, the qualities sought for in friends, and the experience of friendship dissolution.