This study examined the relationship between walking performance rated on the Functional Mobility Scale (FMS) and measures of walking capacity in children with cerebral palsy (CP). A total of 143 participants with spastic CP (GMFCS levels I to III) were rated on the FMS and had assessment of self-selected walking speed (WS), fast 1 minute walk test (1MWT) and six minute walk test (6MWT). For each FMS distance, children rated 6 had significantly better 6MWT than children scored 5; children rated FMS 2, 3, or 4 had lower walking capacity measures but were not clearly distinguishable from each other. The 6MWT was an independent predictor of variation in FMS score, accounting for 20% to 27% of the variance across the three FMS distances. While walking capacity impacts on community mobility in children with CP much of the variance remains unexplained, suggesting that other factors play an important role.