The Proto-Indo-European ( PIE ) tense-aspect system has been reconstructed since the time of Delbrück (1897) as containing a fundamental opposition between two aspect-denoting stems: An Aorist stem, denoting perfective aspect, and a Present stem, denoting imperfective aspect. This reconstruction is, for practical reasons, based almost entirely on Greek and Vedic. Re-examining the Homeric and R̥gvedic data, I argue on semantic grounds against this century-old understanding of the tense-aspect system of PIE . In its place, I reconstruct the “Aorist” indicative as denoting perfect aspect (not perfective), and the “Imperfect” indicative as a simple past tense (not imperfective). Evidence for this reconstruction is based on the consistent usage in the R̥gveda of the Aorist in the meaning ‘have done X ’ (with present reference) and the Imperfect in the meaning ‘did X ’ (especially in narrative contexts)—a distribution which frequently has a precise match in Homer.