Purpose: The authors compared preschool children with co-occurring speech sound disorder (SSD) and language impairment (LI) to children with SSD only in their numbers and types of speech sound errors. Method: In this post hoc quasi-experimental study, independent samples t tests were used to compare the groups in the standard score from different tests of articulation/phonology, percent consonants correct, and the number of omission, substitution, distortion, typical, and atypical error patterns used in the production of different wordlists that had similar levels of phonetic and structural complexity. Results: In comparison with children with SSD only, children with SSD and LI used similar numbers but different types of errors, including more omission patterns ( p < 0.001, d = 1.55) and fewer distortion patterns ( p = 0.022, d = 1.03). There were no significant differences in substitution, typical, and atypical error pattern use. Conclusions: Frequent omission error pattern use may reflect a more compromised linguistic system characterized by absent phonological representations for target sounds (see Shriberg et al., 2005). Research is required to examine the diagnostic potential of early frequent omission error pattern use in predicting later diagnoses of co-occurring SSD and LI and/or reading problems.