In the study reported here, we explored writing processes employed by 70 undergraduate learners of English as a Foreign Language (EFL) through questionnaires and think-aloud protocols. Then we looked for possible differences in the writing processes employed by high- and low-aptitude learners. We observed that learners with higher aptitude scores devoted more attention to clausal complexity than those with lower levels of aptitude. Moreover, they resorted less frequently to their mother tongue while writing texts in English. High-aptitude EFL learners also used more global planning strategies than their low-aptitude peers and edited while writing much more frequently. Our review showed that even though aptitude has been extensively researched in second language acquisition and shown to correlate with the level of success in different skills, it has rarely been considered in relation to writing processes. We suggest that, as classroom teachers, EFL writing instructors accumulate and incorporate knowledge of their students' aptitude in deploying their teaching strategies.