This investigation examined the development of young children's behaviors on swings in the outdoor play environment and their emerging understanding of the physics principles associated with those behaviors. The children's language interactions were also examined in an effort to determine the relationship between language and cognitive development in their construction of physical knowledge. The procedures involved observing the children's behaviors and collecting samples of their spontaneous language interactions during their swinging activities. Informal interviews were also conducted with individual and groups of children. The findings indicate that young children's swinging behaviors develop in eight hierarchical stages. As these behaviors develop, children experiment with the physics principles of balance, gravity, force, resistance, and resonance. Children's swinging behaviors develop in a social context. Many early behaviors are acquired through observing and modeling other children. Language provides the medium for more-experienced peers to assist novice swingers through encouragement and direct instruction. The stage development of swinging behaviors is compared to Cratty's Theory of Perceptual-Motor Development and Harrow's Taxonomy of the Psychomotor Domain. Children's cognitive processing and language interactions are discussed in the context of Piagetian and Vygotskian theories of development. Implications for instruction and suggestions for further research are discussed.