The importance of comparison and message-formulation skills in referential communication was studied with severely mentally retarded children. A store game task was used that required the child to communicate a choice of one or two objects on a shelf. Comparison training taught the children to select the appropriate object when paired with a similar but inappropriate object. Message training taught the children to communicate by pointing and/or gesturing. Results indicated that combined comparison and message training produced higher communication accuracy than did comparison training alone. Comparison training, however, increased subjects' accuracy of communicating as compared to an untrained control group. A parallel pattern of results was found for communication frequency. The training groups either maintained or improved their communicative performance in a near-generalization task, suggesting that they learned communicative behavior and not merely task-specific behavior.