This study investigates the effect of grammatical aspect marking in Dutch sentences, on speakers’ estimations of the duration of highly familiar, everyday events. We first established the ‘inherent’ or natural duration of different events (Exp. 1). This was then used for the manipulation of aspect (Exp. 2). Participants dragged a slider across the computer screen to estimate the duration of progressive and non-progressive event descriptions. Findings show how the progressive form extends duration estimations for short events, whereas it shortens the perceived duration of inherently medium and long events. We interpret this as psycholinguistic evidence for the function of aspect in Dutch, i.e., giving an ‘inside’ view of the event and focusing a specific internal time span of the event.