Journal of Educational Psychology, Vol 118(7), Oct 2026, 1079-1107; doi:10.1037/edu0001034
A basic responsibility of schools worldwide is to teach students to write effective argumentative texts. To meet this objective, teachers need access to evidence-based practices for writing such texts. In this meta-analysis, we examined if the argumentative writing of students in Grades 1–12 can be improved through instruction. Our meta-analysis included published and unpublished studies testing writing treatments with experimental or quasi-experimental designs (with pretests). Effect sizes (ESs) were computed for all writing and content learning outcomes at posttest and maintenance. Across 185 treatment/control comparisons involving 22,216 students, instruction had a positive and statistically detectable impact on students’ argumentative writing immediately following instruction (ES = 0.52), and on maintenance probes administered up to 15 weeks later (ES = 0.69). Instruction to improve argumentative writing also enhanced content learning (ES = 0.38). In addition, a variety of different instructional approaches enhanced students’ argumentative writing on all measures collectively at posttest including dialogic instruction (ES = 0.89), strategy instruction (ES = 0.78), peers working together (ES = 0.55), knowledge building (ES = 0.35), prewriting (ES = 0.28), feedback (ES = 0.26), and goal setting (ES = 0.22). At maintenance, strategy instruction evidenced a positive and statistically significant impact on argumentative writing (ES = 0.75). Implications for practice, research, and theory are discussed. (PsycInfo Database Record (c) 2026 APA, all rights reserved)