Students' mental health have a greatest impact on wellbeing and academic performance, also is often affected adaptation to the university life. This study examines the proportion of students with a positive and negative affect balance, and the relationship between affective wellbeing and academic self-efficacy and performance. It also analyzes how psychological wellbeing and academic self-efficacy predict affective wellbeing and academic performance. In a sample of 200 undergraduate students (M = 19.07 years), it was found that positive affect decreased and negative affect increased during the second academic year. The majority had a positive affect balance (AB). Psychological wellbeing predicts positive emotions and its achievement dimension predicts academic performance. 53% of participating students maintained a positive AB, 14% maintained a negative AB and 21% went from a negative to a positive AB one. The change from a positive to a negative AB (10%) is associated with an increase in psychological wellbeing, suggesting a process of post-stress growth in relation to the challenges of university life.