Friendships are more group-oriented in the United Kingdom than in Japan.

Friendship is a common and complex social bond. Among friendship practices yet to be fully understood are group- versus dyadic-oriented friendship styles, or whether people socialize with one versus multiple friends at a time. We report two studies comparing friendship styles and relational mobility among 1674 young adults (18-35 years old) in Japan and the United Kingdom. Respondents from both countries completed the Friendship Habits Questionnaire, a new measure of dyadic- versus group-oriented friendship styles. Participants also estimated their friendship group size and time spent in friendship groups versus dyads, and completed a scale of relational mobility. Participants' group-oriented friendship style, assessed with the Friendship Habits Questionnaire, was associated with larger friendship groups and more time spent in groups, rather than dyads of friends. Compared to Japanese, participants from the United Kingdom had more group-oriented friendship styles and were more relationally mobile. Moreover, group-oriented friendship styles were associated with higher relational mobility. These findings provide insights into models of friendship and social relationships promoted across diverse cultural settings.