The study aimed to prospectively examine the association between different sedentary behaviors and the risk of depression. We included 12,691 Spanish university graduates (mean age: 36.7 year; SD: 11.5), participants of the Seguimiento Universidad de Navarra cohort (the SUN Project), initially free of depression who were followed-up fir a median of 10.9 years. Based on items presented in our baseline questionnaire, time spent in four sedentary behaviors (hours/day) were evaluated: overall sitting time; TV-viewing; computer use; and driving. Participants were classified as incident cases of depression if they reported a physician diagnosis of depression in at least one of the followup assessments conducted after the first two years offollow-up. Cox regression models were used to assess the relationship between sedentary behaviors and depression. A total of 560 incident cases of depression were identified during follow-up. We found no significant association between overall sitting time, TV-viewing or driving and risk of depression. On the other hand, computer use was directly associated with the risk of developing depression during the follow-up (p-value for trend = 0.020), with the participants in the highest quartile of computer use (3.64 to 10 hours/week) having a higher risk of developing depression (HR = 1.33; 95%CI: 1.05-1.70) than those in the lowest quartile (0 to 0.25 hours/week) after adjusting for potential confounders. Prolonged use of computer was independently associated with an increased risk of developing depression among young middle-aged adult university graduates from a Spanish cohort.