Many historical researchers today refer to residents living in apartment buildings in the high-growth period of Japan. The residents of apartment buildings are significant subjects of historical studies in cases that consider the relation between individuality and solidarity in urban areas. This viewpoint is relevant to the historical study of adult education. In the high-growth period of Japan, people involved in adult education actively discussed the possibility of the solidarity of apartment residents and possible methods of adult education to create such solidarity. Nowadays, however, researchers on adult education no longer refer to the arguments from that period. Considering the above, this paper presents an outline of the arguments by those involved in adult education regarding the residents of apartment buildings. These arguments can be categorized as follows: one is based on a standpoint that presupposes the solidarity created by residential movements, and the other is based on the standpoint that demands “neutral” solidarity among residents. Each standpoint, however, shared the conviction that the solidarity of residents was indispensable, and the understanding that the residents had already fostered their own solidarity, at least to a certain extent. Furthermore, the advocates for each standpoint who presupposed “pure” solidarity sometimes ignored the heterogeneity of the residents.