This study aimed to examine the Collective Efficacy (CE) and Group Cohesion (GC) of players belonging to Japanese high school and university rugby teams, and to verify the associations between these concepts and educational stage and playing opportunities. The sample comprised 766 male high school and college rugby players, who belonged to highly competitive teams that have participated in national competitions. The breakdown of the sample was as follows: high school-roster players (116); high school-non-roster players, (206); university-roster players (108); and university-nonroster players (336). The survey was conducted in-season for control purposes, and only the winning teams in matches preceding and following the survey were targeted. The Japanese translated version of the Collective Efficacy Questionnaire for Sports (CEQS) was used to verify CE, and a Japanese translated version of the Group Environment Questionnaire (GEQ) was used to verify GC. Furthermore, two-way analysis of variance was performed on the values of the dependent variables for each level of the independent variables of educational stages (high school, university) shown as the total score of CE. Simple main effects analysis results indicated that, in the case of high school and university students, roster players displayed higher values than non-roster players. In addition, in the case of roster and non-roster players, high school students displayed higher values than university students. On the other hand, no interaction was shown for the total score of GC. A main effect of educational stage was observed in the analysis results, where high school students displayed higher values than university students. Moreover, regarding playing opportunities, roster players displayed higher values than non-roster players.In addition, this study's results demonstrate that all subscales of both concepts displayed similarities to the total scores; strongly suggesting that an association exists between different educational stages and playing opportunities, as well as between the concepts themselves. This showed that differences in CE and GC arose from differing educational stages and playing opportunities. The findings obtained in the present study can provide helpful insights that inform coaching and management of team sports in season.