The development of mature fundamental movement skills is an important step in the lives of children because these skills form the foundation for lifelong physical activity. Currently several instruments measure children's fundamental movement skills. The Test of Gross Motor Development (TGMD, Ulrich 1985) is one of the most popular instruments to assess children's fundamental movement skills. The instrument has been used in physical education settings, and also to examine the movement competence of individuals with disabilities in numerous research studies. Although the instrument has demonstrated good psychometric property for normative data, no cross-validation study has been reported for children with mental retardation (MR). The purpose of this study was to evaluate psychometric properties of the second edition of TGMD (Ulrich, 2000) for youth with mental retardation. Participants in this study were 1067 youth with MR aged 11 to 18 years (690 males - 377 females). All participants were tested with the second edition of TGMD. Items on the locomotor skills subtest included: (a) running, (b) galloping, (c) standing long jump, (d) hoping, (e) leaping, and (f) sliding. Object control subtest skills were (a) striking, (b) dribbling, (c) catching, (d) kicking, (e) throwing, and (f) rolling activity. All activities include 3 to 4 qualitative performance criteria to assess the level of motor skill development. A confirmatory factor analysis was employed to examine the structure of TGMD to youth with mental retardation. Because there is no single accepted index of model fit, GFI, CFI, NFI, RMSEA, and the ratio of chi-square and degree of freedom (c2/df) were used to examine the structure of the test. Composite scores of six activities from the locomotor subtest were entered as "locomotor construct" and composite scores of object control activities were entered as "object control construct." Internal consistency reliability was employed to examine reliability evidence. A confirmatory factor analysis reveals GFI=.96, CFI=.96, NFI=.97, RMSEA=.06, and c2/df=4.85. Four of five goodness of fit indices were considered to be good. Only the RMSEA did not meet the general criteria. This appears related to the larger performance variability of children with MR. Cronback a from locomotor subtest, object control subtest, and the total battery were .83, .86, and .91, respectively. Reliability coefficient appears to be excellent. Considering all psychometric properties, TGMD appears to be a good instrument to assess youth with MR from 11 to 18 years of age.Keyword(s): adapted physical activity, measurement/evaluation