The present study examines the influence of L2 English on the acquisition of perfective and imperfective aspect in L3 Spanish among German-speaking learners. We will argue that English will be activated as the default transfer source due to principles of acquisition, which are similar for both the L2 and the L3, and because of structural similarities between both languages. The analysis is based on data from 36 German-speaking learners with varying levels of knowledge of aspect in English, their L2, and learning Spanish. For data elicitation, two semantic interpretation tasks were used. The findings show that aspectual knowledge in L2 English affects the acquisition of L3 Spanish past tenses. However, the positive effect is not comprehensive, but rather, restricted to certain semantic contexts (e.g., past/perfective contexts). The discussion points to the possible effects of oversimplified one-to-one-mappings of form and meaning between L2 English and L3 Spanish.