The study was designed to test the impact of study interests on achievement, considering the mediating role of future time perspective and basic positive affect (attentiveness, joviality and self-assurance). A total of 675 Italian students attending 10th and 11th grade of high school (F = 342, 50.7%) were involved in the current study. Students' ages ranged from 16 to 19 years (M[subscript age] = 17.44 years; SD = 0.84 years). Study interests and scores were self-reported by students; furthermore, they completed the Italian version of the Zimbardo Time Perspective Inventory and Positive and Negative Affect Schedule -- Expanded Form. To test mediational effects, we used a multiple mediator model. Results showed that future time perspective and attentiveness partially mediated the relation between school interests and achievement. Practical tips on intervention programs to counteract school failure are provided.