A modeling procedure involving dynamic interactions was used to train three language-delayed preschool children to emit five-element syntactic responses. A single-subject multiple baseline design using within- and across-subject replication was employed to study the acquisition of expanded "agent-action-object" sentences and the spontaneous generation of this form in the natural environment. A familiar person, using an object known to the child, demonstrated a common action, and the symbolic form which described this event was modeled for the child. The generalization and maintenance of the lexicon and syntax trained were tested by contextual probes and responses to video tape presentations. The result demonstrated the effectiveness of the training strategy. Probes revealed generalization and maintenance of both lexical and syntactical forms acquired in treatment. Significant increases in each S's spontaneous usage of the basic syntactical form in the natural environment, i.e., the classroom during free play, were documented. (Author/SB)