The study investigated the effects of the Modified Alternative Co-Teaching Approach (MACTA) on student algebraic procedural fluency (the ability to perform mathematical algorithm accurately and efficiently). The study used the quasi-experimental two-group pretest-posttest design that involves both quantitative and qualitative approaches. The study utilized two intact classes of a laboratory school in Bay, Laguna. One section was exposed to the Modified Alternative Co-Teaching Approach (MACTA) and the other section was exposed to the Conventional Teaching Approach (CTA). Comparison of the student algebraic procedural fluency between MACTA and CTA groups showed no significant difference between the two groups, but students in the experimental group expressed substantial number of positive remarks about the teaching approach. The design of MACTA including smaller class size, more student-student interaction, and increased collaborative activities is believed to promote increase in procedural fluency, and positive attitude provided longer term of implementation.