Purpose: This study involved prospective longitudinal data on 5 late talkers to provide information about the course of phonological development in order to identify possible predictors of delayed versus deviant development.

Method: Five children (3 boys, 2 girls) were identified as late talkers and divided into a younger group and an older group. Each child was followed monthly for 10 to 12 months (22–33 months for the younger group and 30–42 months for the older group). Two types of monthly language samples (free play and elicited) were obtained to describe the individual courses of phonological development for each child. Independent and relational analyses were completed at each age to describe word-initial and word-final phonetic inventories, syllable structure, syllable diversity, percentage of consonants correct (PCC), sound variability, and error patterns.

Results: The results indicated that 3 of the children resolved their late onset of speech by 33 to 35 months of age. In addition to quantitative factors, (e.g., limited phonetic inventory, lower PCC, and more sound errors), qualitative variables (e.g., atypical error patterns, greater sound variability, and slower rate of resolution) also were identified as potential markers of long-term phonological delay.

Clinical Implications: This study provides information to clinicians so they can identify those children who are less likely to resolve their late onset of phonological development without direct intervention. Procedures are described for assessing early linguistic behaviors that incorporate independent and relational analyses on more extensive speech samples (elicited and free play). From these analyses, clinicians can examine quantitative and qualitative variables to differentiate phonological delay from deviance.