This study investigated children’s cooperative problem solving (CPS) behaviors during play in classrooms and associated influencing factors (school, age, and gender) in a Chinese kindergarten and U.S. early learning center. Four- and five-year-old participants (n = 39) were from one Chinese kindergarten and one U.S. center. They were video recorded during free play in the classrooms. The video footage (n = 2340 min) was coded using the coding system adapted from Ramani’s work (Merrill-Palmer Quarterly 58:159–190, 2012), and a two-way MANOVA and multiple regression were conducted. The results indicated significant school and age differences in terms of children’s CPS-related behaviors; in addition, school predicted the children’s frequency of coordinate behavior, and age predicted the children’s use of physical demonstration, explanation, and imitation. (author abstract)