Abstract: Based on a survey in 14 kindergartens and 14 primary schools in urban and suburban areas of Beijing, this study made a comparision on affiliation, between 3 to 12-year-old onlies and non-onlies.The subjects were 482 onlies and paired nononlies, including 885 suburban children and 579 urban children. The methods mainly involved questionnaires, supplemented by observation, interview, case study and peer evaluation.The resurts showed that there was no significant difference in affiliation between onlies and nononlies in the urban areas, and the same was true between only-girls and non-only-girls in the suburban areas, significant difference was only found between only-boys and nononly-boys in the suburban areas (P<0.02).This study also explored the factors in fluencing the only-child's affiliation. Analysis shows: the collective life in a kindergarten and the abundant experience of social participation are favourable to the development of the only-child's affiliation.

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