The aim of the study is to investigate the leisure involvement and happiness levels of the individuals who have any fitness center membership. Screening model was used in the research. The sample group of the research was composed of a total of 599 voluntary participants, 260 being "females" and 339 being "males", who were using fitness centers and were selected using improbable purposeful sampling method. "Oxford Happiness Scale Short Form--OHS-F", developed by Hills and Argyle (2002) and adapted into Turkish by Dogan and Cotok (2011) along with "Leisure Involvement Scale--LIS-F", developed by Kyle et al. (2007) and adapted into Turkish by Gurbuz et al. (2018) were used in the study in addition to "Personal Information Form". Descriptive statistical method (frequency, arithmetic mean, standard deviation) was used for the identification of the distribution of the participants' information. In order to determine if the data had normal distribution or not, Shapiro-Wilk test for normality was conducted and in consequence of this test, t-test, single factorial MANOVA, ANOVA and Pearson Correlation tests were administered upon determining that the data were in accordance with parametric test conditions. According to the findings, while there was no significant difference found in the happiness levels in line with the gender, marital status and education levels of the participants; a significant difference was determined in the leisure involvement levels according to education level and gender, and yet no significant difference was found between the leisure involvement level and marital status. Besides, a positively significant relationship was determined between the level of happiness and leisure involvement. The restraints as well as the evaluations for future studies were discussed in this sense.