In order to examine the relationship between personality dimensions and academic achievement motivation and mental well-being, the researchers selected 181 female undergraduate students of Mathematics, Computer, and Architecture, who were studying at Islamic Azad University, Tabriz Branch during the academic year 2011-2012, as the research sample through the use of random stratified sampling method. The participants were evaluated with NEO Personality Inventory (NEO-FFI), achievement motivation scale (ISM), and mental well-being questionnaire. The research method was correlation. Multi-variate regression was used for data analysis .The results showed that there is a negative relation between the personality dimension (neuroticism) and academic achievement motivation and a significant positive relationship between the personality dimensions (extroversion, openness to experience, agreeableness, and conscientiousness) and academic achievement motivation. Furthermore, the results indicated that there is a negative relationship between the personality dimension (neuroticism) and subjective well-being, and a significant positive relationship between the personality dimensions (agreeableness and conscientiousness) and academic achievement motivation. Furthermore, the results indicated that there is a negative relationship between the personality dimension (neuroticism) and subjective well-being, and a significant positive relationship between the personality dimensions (agreeableness and conscientiousness) and subjective well-being. Based on the research findings, it can be concluded that personality dimensions can predict academic achievement motivation and mental well-being.