This study aimed to identify the most fundamental psychological needs by examining participants' descriptions of "most satisfying events" and their ratings of the salience of 10 candidate needs within these events. The 10 needs were derived from various psychological theories, including self-determination theory, Maslow's hierarchy of needs, and Epstein's cognitive-experiential self-theory. The study used three experiments to test the relative importance of these needs: 1. **Study 1** compared the salience of the 10 needs within participants' most satisfying events over the past month and their association with event-related affect. The results showed that autonomy, competence, and relatedness were among the top four needs, consistent with self-determination theory. Self-esteem was also important, while popularity-influence and money-luxury were less significant. 2. **Study 2** replicated the findings in a U.S. sample and a South Korean sample, examining events over the past week. The results were similar, with autonomy, competence, and relatedness again being the most salient needs. In the South Korean sample, relatedness and security were more salient, reflecting the collectivist culture. 3. **Study 3** extended the research to a longer time frame (the entire semester) and asked participants to describe their most unsatisfying events. The findings from this study supported the generalizability of the identified needs across different time frames and cultural contexts. The study concluded that autonomy, competence, and relatedness are among the most fundamental psychological needs, consistent with self-determination theory. Self-esteem was also important, while popularity-influence and money-luxury were less significant. These findings have implications for understanding human motivation and well-being.This study aimed to identify the most fundamental psychological needs by examining participants' descriptions of "most satisfying events" and their ratings of the salience of 10 candidate needs within these events. The 10 needs were derived from various psychological theories, including self-determination theory, Maslow's hierarchy of needs, and Epstein's cognitive-experiential self-theory. The study used three experiments to test the relative importance of these needs: 1. **Study 1** compared the salience of the 10 needs within participants' most satisfying events over the past month and their association with event-related affect. The results showed that autonomy, competence, and relatedness were among the top four needs, consistent with self-determination theory. Self-esteem was also important, while popularity-influence and money-luxury were less significant. 2. **Study 2** replicated the findings in a U.S. sample and a South Korean sample, examining events over the past week. The results were similar, with autonomy, competence, and relatedness again being the most salient needs. In the South Korean sample, relatedness and security were more salient, reflecting the collectivist culture. 3. **Study 3** extended the research to a longer time frame (the entire semester) and asked participants to describe their most unsatisfying events. The findings from this study supported the generalizability of the identified needs across different time frames and cultural contexts. The study concluded that autonomy, competence, and relatedness are among the most fundamental psychological needs, consistent with self-determination theory. Self-esteem was also important, while popularity-influence and money-luxury were less significant. These findings have implications for understanding human motivation and well-being.