This study examined the use of cohesive features in 270 narrative and argumentative essays produced by 45 s language (L2) students over a semester-long writing course. Multiple regression analyses were conducted to determine the ability of the computational indices of cohesion (TAACO) variables to predict human ratings of essay quality, recognize any differences in the use of cohesive devices between narrative and argumentative genres, and ascertain which of the cohesive devices varied for each of the genres over time. The results indicated clear differences in how cohesion was signaled between the two genres. Narrative texts relied on the use of connective devices to signal cohesion, whereas argumentative texts relied on the use of global-level repetition. With regard to development, the results were less conclusive but do suggest expansion in the participants’ use of cohesive devices. These results provide important implications for L2 writing pedagogy and assessment.