Purpose: Within General American English (GAE), the grammar weaknesses of children with developmental language disorder (DLD) have been documented with many tasks, including grammaticality judgments. Recently, Vaughn et al. replicated this finding with a judgment task targeting tense and agreement (T/A) structures for children who spoke African American English (AAE), a dialect that contains a greater variety of T/A forms than GAE. In the current study, we further tested this finding for children who spoke Southern White English (SWE), another dialect that contains a greater variety of T/A forms than GAE but less variety than AAE. Then, combining the SWE and AAE data, we explored the effects of a child's dialect, clinical group, and production of T/A forms on the children's judgments. Method: The data were from 88 SWE-speaking children (DLD, n = 18; typically developing [TD], n = 70) and 91 AAE-speaking children (DLD, n = 34; TD, n = 57) previously studied. As in the AAE study, the SWE judgment data were examined both with "A'" scores and percentages of acceptability, with comparisons between dialects made on percentages of acceptability. Results: As in AAE, the SWE DLD group had significantly different "A'" scores and percentages of acceptability than the SWE TD group for all sentence types, including those with T/A structures. Additional analyses indicated that the judgments of the TD but not the DLD groups showed dialect effects. Except for verbal "-s," overt production and grammaticality judgments were correlated for the TD but not for the DLD groups. Conclusions: Children with DLD across dialects of English present grammar difficulties that affect their ability to make judgments about sentences. More cross-dialectal research is needed to better understand the grammatical weaknesses of childhood DLD, especially for structures such as verbal "-s" that are expressed differently across dialects of English.