The activities attended by elementary students are surely not just the classroom lessons only. It includes the participations in classroom and school wide student organizations, in academic and sport competitions sponsored by schools, regions, and states, in self-study and school plays and other performance organized by schools, as well as the participations in after school activities , such as cram schools, dance schools, music and instrument lessons, sport trainings, homework, housework, and leisure activities. It is believed that student participation is somewhat related to their family socio-economic status and to some extent shaping their personality in respect to their self-esteem, autonomy, attitudes towards school, and educational aspiration. This study was designed to examine the interrelationships between student participation, the socioeconomic status of their family , and their personality development . Our data were collected from the survey administered to the fifth graders and the sixth graders in class randomly and systematically selected from two metropolitan elementary schools with a salient descent background in farming and labor in Kaohsiung City and Fonsan City. It was found that both participations in school activities and after school activities favor students more for students from upper socioeconomic status family than for those from lower socioeconomic status family, except sport competitions, homework, and housework. On the other hand, the participation in school activities appears to bear more impact upon self-esteem, autonomy, attitude, and aspiration than does the participation in after school activities. Nevertheless, neither the participation in school activities nor the participation in after school activities can completely explain away the relationship between socioeconomic status and the personality variables. The personality variables of self-esteem, autonomy, attitudes, and aspiration are a reflection in social opportunity structure, particularly, for those at the elementary schools, and also attuned to the earlier findings in the study in social inequality. This study provides information worthwhile for those in academic and education who are concerned with the welfare and the equal opportunity for the poor.