In this research, it is aimed to investigate the predictive role of grit as a personality trait and basic psychological needs satisfaction on subjective well-being among young adults. Participants of this research are 348 voluntary young adults who are final year undergraduate students in the government universities of Istanbul city, Turkey, as well as graduates who work. There are 200 (57.5%) females and 148 (42.5%) males. The average age is 23.01 (sd=2.52). Data collection tools used in this research are "Subjective Well-Being Scale" (Tuzgöl-Dost, 2015), "Revised Grit Scale" (Duckworth and Quinn, 2009) and "Basic Psychological Needs Satisfaction Scale" (Deci and Ryan, 1991). Pearson product-moment correlation coefficient, hierarchical regression analysis and independent group t tests are conducted. According to the findings, female participants have higher subjective well-being levels than males. Relatedness satisfaction sub-scale score from basic psychological needs satisfaction scale and total score of basic psychological needs satisfaction are found to show a significant difference in favor of females. Regression analysis concluded that grit, satisfaction of three basic psychological needs (autonomy, competence and relatedness) and gender are the meaningful predictors of subjective well-being for young adults. Satisfaction of three basic needs predicts subjective well-being stronger than grit and gender. Besides, a positive and statistically significant relationship between the satisfaction of three basic needs and grit tendency is concluded. Findings are discussed in the light of the related literature. Suggestions are made for further researches and for school counsellors and mental health professionals.