Abstract: Two studies evaluated the computational abilities of US fifth-graders in the University of Chicago School Mathematics Projects curriculum (UCSMP), a reform-based program. In Study I, the UCSMP students far outperformed the comparison fifth graders on a test of mental computation. On two additional fraction problem, the UCSMP fifth graders outperformed comparison seventh graders. This study replicated findings from the previous year. In Study 2 UCSMP students scored slightly higher than comparison students on a paper-and- pencil computation test, although few significant differences were found. However, major differences were found in the types of solution methods used by the two group on the written test. Aspects of the UCSMP curriculum, especially the focus on student discussions of multiple solution methods, are discussed in conjunction with these findings.