Introduction: Findings on the association of speaking different languages with cognitive functioning in old age are inconsistent and inconclusive so far. Therefore, the present study set out to investigate the relation of the number of languages spoken to cognitive performance and its interplay with several other markers of cognitive reserve in a large sample of older adults. Method: Two thousand eight hundred and twelve older adults served as sample for the present study. Psychometric tests on verbal abilities, basic processing speed, and cognitive flexibility were administered. In addition, individuals were interviewed on their different languages spoken on a regular basis, educational attainment, occupation, and engaging in different activities throughout adulthood. Results: Higher number of languages regularly spoken was significantly associated with better performance in verbal abilities and processing speed, but unrelated to cognitive flexibility. Regression analyses showed that the number of languages spoken predicted cognitive performance over and above leisure activities/ physical demand of job/gainful activity as respective additional predictor, but not over and above educational attainment/cognitive level of job as respective additional predictor. There was no significant moderation of the association of the number of languages spoken with cognitive performance in any model. Conclusions: Present data suggest that speaking different languages on a regular basis may additionally contribute to the build-up of cognitive reserve in old age. Yet, this may not be universal, but linked to verbal abilities and basic cognitive processing speed. Moreover, it may be dependent on other types of cognitive stimulation that individuals also engaged in during their life course.