Twelve experiments were conducted to determine how each unitary taste quality is affected by each of the other taste qualities. Solutions containing stimuli appropriate to both taste qualities were rated for intensity of sweetness, saltiness, sourness, or bitterness by a group of judges. Each experiment was independently replicated. In most cases, the effects were those of simple enhancement or masking, or no effect at all was found. Certain exceptions and complex relationships occurred, and recommendations for follow-up research were made. Various aspects of the method and design were discussed.