The purpose of the study was to investigate the effects of a Special Olympics (SO) Unified Sports (UNS) soccer program on psycho-social attributes of youth with and without intellectual disabilities (ID). Participants were 76 male youth with (n = 38) and without (n = 38) ID. Participants with ID were randomly allocated into a SO athletes group (n = 23, mean age = 14.5; SD = 1.2 years) and a control group (CG) (n = 15, mean age = 14.5; SD = .8 years). Twenty-three randomly selected youth without ID formed the partner group (mean age = 14.1; SD = .9 years) and 15 youth without ID (mean age = 13.8; SD = .5 years) formed the CG. Instruments included the Friendship Activity Scale (FAS) (Siperstein, 1980), the Adjective Checklist (Siperstein, 1980), and the Children Behavior Checklist (Achenbach, 1991). The soccer training program lasted eight weeks, 1.5 h per session, three times per week, in addition to school physical education (PE). The CG did not participate in any sports in addition to PE. The findings showed that the UNS program was effective in decreasing the problem behaviors of youth with ID and increasing their social competence and FAS scores. In addition, the program was found to be effective in improving the attitude of youth without disabilities toward participants with disabilities. In conclusion, the present findings demonstrate the utility of a UNS program for both youth with and without disabilities. (C) 2011 Elsevier Ltd. All rights reserved.