This paper proposes a new theory of Conditional Social Equality (CSE) which in some ways challenges the theory of cumulative advantage/disadvantage (CAD), which postulates that inequalities and social divisions necessarily increase over time. Using evidence from informal learning groups in Men's Sheds in three countries, we conclude that some social divisions between homosocial groups, in this case groups of older men, may actually decrease -- but only under certain conditions. Male-gendered learning groups that were relatively homogeneous by age helped erase class divisions and softened gender stereotypes. Our theory of conditional social equality (CSE) predicts the following: (1) in-group homogeneity can enable the acceptance of some aspects of heterogeneity; (2) some other aspects of in-group heterogeneity may not be tolerated, thus maintaining in-group cohesion; and (3) in-group homogeneity and boundary setting towards out-groups may be prerequisites for the acceptance of (some) aspects of in-group heterogeneity. All of this has important implications for adult learning in both heterogeneous and homogenous groups.