The purpose of this study was to examine in which contexts prosocial behaviors took place among two-year-old toddlers during free play when they could have a dynamic interaction with one another and how their prosocial behaviors turned or evolved into another related behavior. A research question was posed: 1. In which emergent contexts do two-year-old toddlers show prosocial behaviors during free play? The participants in this study were eight two-year-old males in D daycare center located in B city. An observation was conducted for two hours each in the morning and in the afternoon, three times a week, during their normal classroom hours between 9 a.m. and 6 p.m. The major findings of the study were as follows: First, the participants shared what they played with when they showed attention and affection to the items. Second, when several participants showed prosocial behaviors, the others imitated the behaviors as models or showed another related prosocial behavior. Third, when their teacher resolved conflict or provided general intervention for challenging situations, the participants were stimulated to show prosocial behaviors or to help one another thanks to the influence of her authority. Fourth, the participants were often in conflict with one another due to their egocentric thinking. Based on their egocentric thinking, the participants chose to show prosocial behaviors as a conflict resolution method. When the participant had a conflict with his peers who usually had more social attachment than the others, they were able to manage and mediate their conflicts without an argument against each other.