Substantial evidence indicates that teacher-delivered schema-based instruction (SBI) facilitates significant increases in mathematics word problem solving (WPS) skills for diverse students; however research is unclear whether technology affordances facilitate superior gains in computer-mediated (CM) instruction in mathematics WPS when compared to teacher-mediated (TM) instruction particularly for low-performing students. This study investigated the differential effects of CM-SBI compared to TMSBI on mathematics WPS performance of mathematically low-achieving third-grade students using two commercially available packages (i.e., GO Solve Word Problems computer software [Tom Snyder Productions, 2005] and Solving Math Word Problems: Teaching Students with Learning Disabilities Using Schema-Based Instruction [Pro-Ed, 2007]). In addition, teacher and student satisfaction with strategy instruction and program materials were examined. Twenty-five students from one school district were randomly assigned to either a CM condition or a TM condition. Both conditions employed SBI that guided students to identify the problem type, and map the problem features using diagrams. Further, both conditions employed key instructional design principles and mathematics problem solving instructional features identified in the literature as effective for teaching students with disabilities (e.g., schematic diagrams, worked examples, visual representations, modeling). Intervention in both conditions consisted of 15 instructional sessions spanning six school weeks and session times remained constant between conditions. A pretest-posttest-delayed posttest repeated measures design (2 Group x 3 Times) with random assignment evaluates WPS gains of the two conditions using criterion-referenced WPS pretest, posttest and maintenance tests. Overall, results indicated that students in both conditions made significant gains in WPS performance and maintained gains after four weeks with no significant differences between conditions. Results suggest that SBI was effective at increasing and maintaining student skills in WPS performance regardless of instructional mode. Results also revealed no significant difference between conditions on student satisfaction or motivation and the teachers' preference for the TM curriculum over the computer software was indicated. Results suggest that the most important variable in terms of student gains in WPS acquisition and maintenance for mathematically low-performing students in CM settings is the strategy implemented (e.g., SBI that employs key instructional design features). Implications, limitations and recommendations for future research are discussed.