This study was aimed at examining the effectiveness of Structure-Based Writing Assignments (SBWA) in minimizing learners' grammatical errors in English compositions. The assignments were focussed on grammatical items the learners had found the most difficult. This classroom action research involved 17 students in an advanced writing class. The results show that there were significant differences in the frequency of the learners' grammatical errors in the use of verb phrases, complex sentences, pluralization, and noun determiners before and after the provision of SBWA. The findings suggest that SBWA is an effective remedial program given in a writing class as it contributes to the development of learners' competence in English grammar