This study examined age effects on real-life language use and within-person variations in language use across social contexts. We used the Electronically Activated Recorder (i.e., a portable audio recorder that periodically records sound snippets) to collect over 31,300 snippets (30 seconds long) from 61 young and 48 healthy older adults in Switzerland across four days. We examined vocabulary richness and grammatical complexity across the social contexts of (a) activities (i.e., socializing, working); and (b) conversation types (i.e., small talk, substantive conversation). Multilevel models showed that vocabulary richness and grammatical complexity increased during socializing and substantive conversations, but decreased in small talk. Moreover, young adults produced shorter clauses at work than not at work. Furthermore, compared with young adults, older adults used richer vocabulary and more complex grammatical structures at work; and used richer vocabulary in small talk. In contrast, young adults used richer vocabulary than older adults during non-socializing and non-working occasions, such as watching TV and exercising. Results are discussed in the context of cognitive aging research with a novel emphasis on context.