The aim of the present study was to investigate the effect of serious leisure time on life satisfaction of disabled people and veterans with happiness as a mediator. The research method was applied in terms of purpose and descriptive-correlational survey in terms of data collection method. The statistical population of this study was disabled people and veterans of Khorasan Razavi, including physically, visually, and hearing disabled people and veterans. As a sample 183 questionnaires were finally completed. Also, convenience sampling method was used to select the sample. The data collection tools were standard questionnaires of serious leisure time, life satisfaction questionnaire, and Oxford Happiness Questionnaire. The reliability of the questionnaires was examined and confirmed with Cronbach's alpha. The validity of the questionnaires was confirmed with the opinions of 10 professors of sports management and psychology. The results of the study showed that serious leisure time has a positive and significant effect on the happiness of disabled people and veterans. Happiness also has a positive and significant effect on the life satisfaction of disabled people and veterans. Serious leisure time has a positive and significant effect on the life satisfaction of disabled people and veterans. In addition, happiness plays a mediating role in the relationship between serious leisure time and the life satisfaction of disabled people and veterans. Therefore, it can be said that favorable planning for the continuous participation of disabled people and veterans in serious leisure activities can improve the life satisfaction and happiness of this segment of society.