Spanish spelling, especially the use of written accent marks, is a major stumbling block for Spanish heritage language (SHL) learners (Carreira 2002). In fact, Mikulski (2006) found that most SHL learners ranked bettering their spelling and grammar as a very important learning goal. Despite its importance in literacy development and its perceived value as a signal of an accomplished writer, few empirical studies have addressed spelling and use of accent marks. To address this gap, the present study evaluated a step-bystep instructional approach focusing on stress identification, which was delivered in three computer-based training sessions. The sessions consisted of listening exercises containing exaggerated and contrastive stress. Additionally, students received an introductory lesson and two explicit explanations of written accent rules with practice activities. Pre- and post-test results show the instruction effectively improved students' stress identification skills and ability to add written accent marks when appropriate. In addition, results find that the most complex aspect of learning accent use is identification of the stressed syllable. Poor spelling ability can affect students' attitudes toward writing, their fluency, and their self-confidence as writers. Therefore, it is important that SHL learners master correct accent placement through effective instructional procedures.