The relationship between play unit complexity and the behavior of 24 normal 3- to 6-year-olds was examined in three Viennese kindergartens. Play units were rated as simple (a unit with one obvious use and no sub-parts or juxtaposition of two essentially different play materials, e.g., puzzles or clay), or super (a complex unit which has three or more play materials juxtaposed, e.g., blocks, cars, and plastic figures combined into one play unit). Results showed that play unit complexity is significantly related to play group size, degree of involvement, and amount of pleasurable affect exhibited in a child's play. Although all three kindergartens were crowded, results suggested that architectural design (i.e., the number of rooms in the kindergarten) affected the incidence of interrupted play. (Author/JMB)