To interrogate the field’s current understanding of writing as central to learning in the sciences, this study offers results from a qualitative, emic study of college students and their scientist mentors at work in an NSF-sponsored Research Experience for Undergraduates. I observed that the work of this professional research laboratory mainly recruited and developed literacies, such as manual dexterity and visual acuity, other than language-based ones. Describing here the various laboratory activities that fostered higher-order thinking and knowledge transformation, I conclude that “writing to learn” research must consider how writing fits in with an ever-developing understanding of the complexity of learning.