Abstract
In this study, we observed 2- to 3-year-olds at play in a nursery school over a six-month period and investigated how they create shared themes. We found that shared themes varied gradually over a period of time. In the first three months, the shared theme was characterized as "reciprocal imitation". In reciprocal imitation, children can feel "sameness" and make contact with one another by behaving in a similar way and with similar objects to their peers. After the initial three months, the children enjoyed the "make-believe theme" by uttering the introduction of make-believe play. Although their make-believe play depended on a routine (or format) at the beginning, they were eventually able to share goals and cooperate with one another in the absence of routine.
