The purpose of this study was to examine the effects of happiness improvement program on psychological variables which were happiness feeling, self-esteem, interpersonal relationship, internal-external locus of control, stress, coping, perceived performance and physiological variables such as cortisol and serotonin of collegiate badminton players. The participants consisted of 10 collegiate badminton players. Happiness improvement program for collegiate badminton players was developed by previous literatures, in-depth-interview, psychological test data, and consultation of happiness improvement experts. The happiness improvement program consisted of 12 intervention program: orientation, rapport development and the understanding happiness, self-esteem enhancement techniques, interpersonal relationship strategies, stress and coping management, peak performance methods, and action plan of happiness improvement program. Each program was applied to participants in about 90-120 minute a session(2-3 times session a week). The instruments of this study were made up of three broad categories: (a) psychological data, b) physiological data, and (c) qualitative data. Firstly, happiness improvement program significantly increased happiness feeling, self-esteem, internal-external locus of control, interpersonal relationship capability, coping skills of collegiate badminton players. Secondly, happiness improvement program significantly decreased stress of collegiate badminton players. Thirdly, participants positively perceived the effects of happiness improvement program on psycho-physiological variables. The limitations of this study and future implications were discussed.
