Purpose: Analyses of language production of individuals with traumatic brain injury (TBI) place increasing emphasis on microlinguistic (i.e., within-sentence) patterns. It is unknown whether the observed problems involve implementation of well-formed sentence frames or represent a fundamental linguistic disturbance in computing sentence structure. This study investigated the cognitive basis for microlinguistic deficits in individuals with TBI. Method: Fifteen nonaphasic individuals with severe TBI and 6 age- and education-matched non brain-injured adults participated in this study. Monologic discourse samples were analyzed for pausing patterns, mazes, errors, and abandoned utterances. Measures of cognitive abilities were correlated with the sentence measures. Results: The speakers with TBI produced more pauses between clauses (but not within clauses) as well as more mazes than did the non brain-injured speakers. Significant regression models were built. Raven's Coloured Progressive Matrices (Raven, 1965), a measure associated with working memory, predicted pause behavior, and Likenesses-Differences (Baker & Leland, 1967), a measure of executive function, predicted maze behavior. Conclusions: Sentence planning impairments following TBI are associated with deficient organization and monitoring of language representations in working memory. These findings suggest that the deficits are due to problems in the recruitment and control of attention for sentence planning. These findings bear on sentence processing models that emphasize the activation, organization, and maintenance of language representations for accurate sentence production. (Contains 6 tables and 1 figure.)