LAUSR

Objectives: The current study examined prosocial and antisocial behaviors from teammates as predictors of within‐person differences over time in self‐reported prosocial and antisocial teammate behaviors toward teammates and social identity strength. Design: Over a 10‐day period, a daily diary approach was used to collect 848 observations from 100; male, n = 45; female, n = 55 youth hockey athletes who were between 11 and 17 years of age (Mage = 13.24, SD = 1.83). Method: Participants completed daily diaries related to their experiences of prosocial and antisocial behavior from teammates, the prosocial and antisocial behaviors they directed toward teammates, and social identity strength. Linear mixed‐level modelling was used to examine how daily experiences of moral behavior from teammates over‐time were linked to within‐person differences in moral behaviors toward teammates and social identity strength. Results: Multilevel analyses showed significant within‐person variance in athletes' moral behaviors toward teammates and their social identity strength. These differences were predicted by daily experiences of prosocial and antisocial behavior from teammates. Athletes reported a stronger social identity on days they experienced a higher number of prosocial behaviors, and a weaker social identity on days they experienced a higher number of antisocial behaviors. The frequency of daily experienced prosocial and antisocial behaviors interacted in predicting self‐reported prosocial and antisocial behaviors toward teammates. Conclusion: Daily prosocial and antisocial behaviors from teammates are systematically related to the ways that athletes behave toward their teammates as well as the strength with which they identify with their sport team. HighlightsA daily diary approach was used in youth sport to collect 848 daily observations.Moral behaviors and social identity showed significant within‐person variability.Experienced moral behaviors interact in predicting behaviors toward teammates.Experienced prosocial teammate behaviours positively predicted social identity.Experienced antisocial teammate behaviours negatively predicted social identity.