In this article, I advocate for an enriched view of children's linguistic input, with the aim of building sustainable and tangible links between theoretical models of language development and families' everyday experiences. Children's language experiences constrain theoretical models in ways that may illuminate universal learning biases. However, more than that, these experiences provide a staggering array of test cases and demonstrate the stage‐setting effects of situational, familial, and societal context on language use and uptake. Centering on activity type as an entry point into context, I outline an approach—which I refer to as language in vivo—that draws on both big‐ and small‐data methods to generate grounded, informative, and representative descriptions of children's input. Minimally, this approach complements recent work that uses more bundled input measures. Maximally, an in vivo approach could inspire new questions, insights, and innovations to broaden the coverage and application of theoretical models to individual communities and families.