Simultaneous interpreting (SI) is a complex skill, where language comprehension and production take place at the same time in two different languages. In this study we identified some of the basic cognitive skills involved in SI, focusing on the roles of memory and lexical retrieval. We administered a reading span task in two languages and a verbal digit span task in the native language to assess memory capacity, and a picture naming and a word translation task to tap the retrieval time of lexical items in two languages, and we related performance on these four tasks to interpreting skill in untrained bilinguals. The results showed that word translation and picture naming latencies correlate with interpreting performance. Also digit span and reading span were associated with SI performance, only less strongly so. A graphical models analysis indicated that specifically word translation efficiency and working memory form independent subskills of SI performance in untrained bilinguals.