The study seeks to understand the relation between preschool children's mode of participation and negotiation strategies during play and their theory of mind (ToM) development in the Hong Kong context. Forty-two 5-year-old children were recruited. Their emotional and cognitive ToMs were assessed along with expressive language ability. Children's play was observed twice in naturalistic and laboratory settings. Parents completed a questionnaire on their child's emotional and cognitive ToM development, including demographic information and social economic status indexes. The results showed that 5-year-old Hong Kong children mostly engaged in associative and cooperative play and employed two-way, reciprocal strategies in their play. Parent report of emotional ToM predicted children's play strategy in both naturalistic and laboratory settings. Child measure of cognitive ToM predicted their play strategy in the laboratory setting. The study advocates more play time in kindergarten in order to foster an empathetic generation. (author abstract)