The effects of participation of fifth grade students in the Mathematical Olympiad for Elementary Schools were investigated. Fifth grade subjects at one school who participated in the Mathematical Olympiad for Elementary Schools were compared with non-participants in routine and non-routine mathematics problem-solving achievement, non-routine problem-solving process levels, and attitudes towards mathematics. Results indicated that participation positively affected the participants’ non-routine problem-solving process levels but no uniform results were found on the other factors. The importance of appropriate non-routine mathematics problem-solving tests was indicated as a future source of study. A description of the investigation, instruments and results is included. / Master of Arts