In a randomized controlled trial, 205 students were followed from grades 1 to 3 with a focus on changes in their writing trajectories following an evidence-based intervention during the spring of second grade. Students were identified as being at-risk (n = 138), and then randomized into treatment (n = 68) versus business-as-usual conditions (n = 70). A typical group also was included (n = 67). The writing intervention comprised Lesson Sets 4 and 7 from the Process Assessment of the Learner (PAL), and was conducted via small groups (three to six students) twice a week for 12 weeks in accordance with a response-to-intervention Tier 2 model. The primary outcome was the Wechsler Individual Achievement Test-II Written Expression Scale. Results indicated modest support for the PAL lesson plans, with an accelerated rate of growth in writing skills following treatment. There were no significant moderator effects, although there was evidence that the most globally impaired students demonstrated a more rapid rate of growth following treatment. These findings suggest the need for ongoing examination of evidence-based treatments in writing for young elementary students.