The current study, setting a two-fold goal, attempted to see whether the preemptive focus on form (FonF) under either planned or unplanned conditions could contribute to increasing lexical diversity in written narratives and, second, to find whether there was a trade-off between the lexical diversity and accuracy. To this end, 32 beginner learners were selected following a Quick Oxford Placement Test and assigned into two groups to receive preemptive FonF under no-planning and pre-task planning conditions. The analysis of the results through a set ofrepeated measure ANOVAs and independent-samples t-tests revealed that the first group with unplanned condition outperformed the one with pre-task planning in lexical diversity. The results also revealed the trade-off between the lexical diversity and accuracy. That is, both lexical diversity and accuracy were significantly taken care of under unplanned preemptive condition whereas pre-task planning hindered attendingto lexical diversity and, thus, both aspects simultaneously. It was concluded that providing learners with appropriate conditions through form-focused instruction can set the ground for activating their linguistic knowledge and letting them attend to different linguistic aspects during writing.
