This study investigated whether pre-task planning that embeds grammatical guidance to attend to a specific L2 form might be a suitable pedagogical choice in beginning-level foreign language classrooms. First-year high school students of English in Japan were asked to do an oral story-retelling task with a class partner under one of three conditions: without any prior planning (n = 17), after 5 minutes of unguided planning (n = 20), or after 5 minutes of planning with guidance in the form of a grammar handout about English relative clauses (n = 19). The resulting narratives were analyzed for task essentialness, amount and quality of use of relativization, and global complexity and fluency. It was found that the guided planning group produced more and more accurate relative clauses in their narratives than the other two groups, to both statistically significant and large degrees, while at the same time exhibiting global levels of complexity and fluency that were similar to those of the other two groups. The results show that guided planning can succeed in creating favorable conditions for striking a pedagogical balance between communication and grammar, even with high school learners at incipient levels of proficiency and under conditions that are typical of many foreign language contexts. (Contains 6 tables.)