The aim of this dynamic prospective follow-up study was to assess the association between olive oil consumption and the likelihood of weight gain or the incidence of overweight or obesity in a large Mediterranean cohort of 7,368 male and female Spanish university graduates (the SUN Project) who were followed for a median period of 28.5 mon. A validated Food Frequency Questionnaire was administered at baseline, and respondents also completed a follow-up questionnaire after 28.5 mon. Changes in participants' consumption of olive oil and their weight were assessed during follow-up. A higher baseline consumption of olive oil was associated with a lower likelihood of weight gain, although the differences were not statistically significant. The adjusted difference in weight gain (kg) was -0.16 [95% confidence interval (CI): -0.42 to +0.11] for participants in the upper quintile of olive oil consumption (median: 46 g/d) compared with those in the lowest quintile (median: 6 g/d). For participants with a high baseline consumption of olive oil whose olive oil consumption also increased during follow-up, we found a slightly increased but nonsignificant risk of incidence of overweight or obesity (adjusted odds ratio = 1.19, 95% CI: 0.73 to 1.95). Our study, carried out in a sample of free-living people, shows that a high amount of olive oil consumption is not associated with higher weight gain or a significantly higher risk of developing overweight or obesity in the context of the Mediterranean food pattern.