The results of a study in applied educational psycholinguistics are presented. The project used a theoretical model of communicative competence to develop testing techniques for diagnosing levels of ability in functional language skills, and to develop training techniques to promote the acquisition of speaking and listening skills among elementary school children in three urban metropolitan schools. Three main issues of the study were: (1) Evaluation: a theoretical analysis and description of the communication process was made, and a battery of perceptual, cognitive and linguistic measures were constructed which reliably and validly trichotomised a sample of grade 2 students into low, moderate, and high levels of oral communication competence; (2) Intervention/Training: the evaluation data were used to create an experimental group of low competent subjects who were enrolled in a communication training program to improve their expressive language skills; and (3) Assessment of Training; statistical comparisons were made of experimental versus control subjects and a number of significant training and modeling effects were found on a variety of cognitive and pragmatic-linguistic measures. Two major language functions were discovered--spatio-temporal language, and logical language--and their implications for cognitive and linguistic development were examined. (Author/RL)