Research has suggested that using two or more languages on a daily basis helps older adults maintain a heightened functional state and improves neurocomputational efficiency. In this review, we discuss studies that have examined the effect of life-long bilingualism on age-related cognitive and neural decline, with a focus on discrepancies between different sources of evidence. We intend to outline and characterize factors which might explain inconsistencies between studies claiming that bilingualism has neurocognitive benefits and those that failed to find such evidence. We argue that individual variation in language proficiency and exposure, especially language switching frequency and daily frequency of use of the two languages, likely account for a significant chunk of the inconsistencies found in the literature and constrain the effectiveness of bilingualism as a cognitive and brain reserve factor. Finally, we briefly review studies of cognitive intervention and speculate on the potential of developing language training protocols to increase cognitive and neural resilience in older adults.