Objective: To characterize the language impairments that occur in brain tumor patients using a cognitively oriented theoretical framework. Method: Forty-nine preoperative brain tumor patients completed a new testing protocol (the BLAST) which assesses 8 well documented, “core” cognitive skills required for language: auditory word recognition, accessing semantic knowledge, lexical selection, phonological encoding, verbal short-term memory, goal-driven language selection, verb retrieval, and articulatory-motor planning. Patients were unselected with respect to lesion location. Results: A surprising 65% of patients scored below controls on at least 1 core skill. Patients with left temporal tumors, as a group, had lower scores than the remaining patients on phonological encoding, accessing semantic knowledge and verbal short-term memory (STM). Those with left frontal tumors had the lowest scores on articulatory-motor planning. These findings are broadly consistent with previous studies examining the anatomical substrates of our “core” cognitive processes. Conclusions: We conclude that selective impairments in key language skills are common in brain tumor patients, but many of these are not adequately assessed on conventional aphasia assessments. Our protocol may provide a useful resource for preoperative, postoperative and intraoperative language assessment in this population.