Whilst historically there has been a widespread consensus that teaching grammar has no impact on students' attainment in writing, more recent research suggests that where a functionally oriented approach to grammar is meaningfully embedded within the teaching of writing, significant improvements in writing can be secured. A recent study, using a functionally oriented approach, which found a statistically significant positive effect of such an approach, also found that the approach appeared to benefit higher attaining writers more than lower attaining writers. The study reported here set out to investigate specifically whether functionally oriented approach to teaching grammar in the context of writing might support less proficient writers. A quasi-experimental design was adopted, repeating the principles of the parent study but with the intervention adapted to meet the identified writing needs of less proficient writers. The statistical analysis indicated a positive effect for the intervention group (p < 0.05), and an effect size of 0.33 on students' Sentence Structure and Punctuation. The study demonstrates that explicit attention to grammar within the teaching of writing can support learners in developing their writing, but taken with the parent study, it also highlights that pedagogical choices need to be well matched to writers' needs.