This classroom study examines whether English L2 writers' language use differs depending on the writing task (operationalized as paragraph type), and task conditions (operationalized as individual or collaborative writing). The texts written by English L2 university students in Colombia (N = 26) in response to problem/solution and cause/effect writing tasks were compared in terms of analytic ratings, use of target grammatical clauses, and accuracy. Approximately half of the students wrote individually while the other half collaborated in pairs. Results indicated that the writing task was a significant factor, with cause/effect paragraphs rated higher and having more target clauses than the problem/solution paragraphs. Task condition was also a significant factor, with collaborative texts more accurate than individual texts. Implications for L2 writing pedagogy are highlighted.