The play of children is the means of their learning and growth. Children`s cognitive, emotional, social and physical development is accomplished through their various kinds of play. The questions raised in this study were: Are there any significant differences in the frequency of participation, "as-if" elements and the types of the imaginative play according to the children`s sex, intelligence, fathers` occupation and the number of siblings? Is there any significant difference between the groups of high and low frequency of participation in imaginative play by types of mother-child interaction? The subjects were 118 children of Saemaul nursery schools and kindergartens and 60 of their mothers. Imaginative play was checked 50 times for 15 seconds each during their free play period in the nursery schools and the kindergartens. Mother-child interaction was observed 40 times in a partially-structured setting of 15 seconds duration. The data was analyzed by analysis of variance and t-test with the SPSS computer program. The result indicated significant differences between frequency of childrens` participation in imaginative play by their sex and by their fathers` occupation. That is, there was a tendency for boys to engage in imaginative play more often than girls. The children whose fathers had professional or official occupations engaged in imaginative play more frequently than the children whose fathers were unemployed or unskilled laborers. The result also showed that the "as-if" elements in the imaginative play differed according to children`s sex and fathers` occupation. There was a tendency for the boys to act as agents of the play and combine realistic roles and fantasy roles in the imaginative play more often than girls. In their imaginative play, boys not only used objects similar to the real world but also objects dissimilar from the real world for make-believe. Their were also many interpretative verbalizations and effective sounds in make-believe. The children whose fathers had professional or official occupations transfered their realistic roles more into make-believe with their actions more often than the dhildren with unskilled or unemployed fathers. For their make-believe they used many objects similar with that of the real world and had various role related verbalizations and effective sounds. The result showed significant differences in single imaginative play and social imginative play by the child`s sex and by fathers` occupation. That is, boys layed single and social imaginative play more often than girls. Children whose fathers had undkilled jobs or were unemployed jobs showed the least frequency of particiipation in single imaginative play and social imaginative play. The relationship between frequency of child`s participation in imaginative play and mother-child interaction showed that mothers of high frequency participation children interacted more with their children and encourage them to learn or develop by themselves. They also praised their children, encouraged, interpretated and made tender physical contact with their children more than mothers of low particlpating children.