Written expression is a high-level language process susceptible to impairment given mild traumatic brain injury (mTBI); however, minimal research exists about assessing or treating this aspect of language performance. This study's purpose was to determine the effect of a multicomponent intervention on the written expression of an undergraduate student with mTBI resulting in generalized expressive language impairment. Pretreatment, intervention, and posttreatment sessions extended over 11 weeks. Intervention addressed semantic associations, semantic mapping, proofreading, organization, foundational skills, and goal setting. Data reflected performance on intervention components, writing probes, and pre-posttreatment completion of a standardized writing measure. Calculation and plotting of correct writing sequence percentages revealed substantial improvement. Linear regression analysis confirmed the trend line slope for intervention probes differed significantly from baseline probes. Comparison of pre-posttreatment test results also confirmed substantial improvement. Multicomponent instruction similar to that recommended for other students with writing challenges may be effective for people with mTBI.