Our study examined the effects of Write Start, a classroom-embedded handwriting/writing program on handwriting and writing fluency for first grade students, co-taught by occupational therapists and teachers. Two first grade classrooms received the Write Start and two received standard handwriting instruction. This co-taught program included specific feedback during handwriting practice, small group activities, student self-evaluation, and peer supports. The students were evaluated on handwriting legibility, fluency, and written expression at baseline, immediately after the program, and 6 months later. When performance was compared between the two groups, the students in the Write Start program improved significantly more in legibility (d = .57) and fluency (d = .75) than students who received standard instruction. Gains in handwriting speed (d = .18), average legibility (d = .26), and written expression (d = .25) did not differ significantly between the two groups. A co-taught, inclusive handwriting/writing program can promote first grade students' achievement of lower case legibility and writing fluency.