This study investigated the relationship between perception and production in children's phonological learning to determine whether perceptual confusions could account for the patterns of substitution and deletion found in 2-year-olds' speech. A total of 14 children were presented pairs of toy stimuli, with each pair composed of a familiar item and an unfamiliar nonsense toy. The names of the toys in each pair differed from each other by one or two phonological features. The children were asked individually to name the toys both imitatively and spontaneously and to perform a task that tested whether they could discriminate the two names when the experimenter produced them. The methodology used is recommended in the study of developmental perceptual confusions of speech sounds in children at this age since it is easily administered and scored and can be presented by live-voice without substantial loss of data validity. The data suggest that some minimal pairs of phonemes are easily discriminated by most 24-month-old children, but others are more difficult. Elements which are substituted for each other in childhood speech production are not necessarily the most difficult contrasts to perceive; perceptual confusions probably play a substantial part in childhood speech errors but not all errors are related to perceptual difficulties. (GO)