This study assessed the effectiveness of 5 hours of training on 3-year-old children's comprehension and production of the passive, negative, possessive, and negative passive syntactic structures. A comprehension test identified 20 children who did not evidence understanding of these structures. Subjects were then randomly assigned to experimental and control groups. Experimental subjects received daily training while subjects in the control group received no training. Toys in different arrangements served as exemplars of the structures. A re-administration of the comprehension test to all children after 3 weeks showed significant improvement among experimental subjects, who also performed well on a test for production of these structures. (A drawing illustrating the experimental process and data obtained from the language comprehension tests are provided.) (Author/MF)