Scholarship animating both WAC/WID (Allan, 2013; Gere, et al., 2018; Hendrickson, 2016; Kells, 2007; Reid, et al., 2016) and STEM (Roth, 2003; Roth & Jornet, 2013; Tsui, 2007) has increasingly called for pedagogical attention to learners' lived, embodied experiences of knowing, writing, and becoming in and across disciplinary worlds. As one response to such calls, this article argues for "literate activity" (Durst, 2019; Prior, 1998, 2015; Prior & Shipka, 2003) as a productive approach to addressing people's embodied engagements with semiosis in unfolding moments that are historically dispersed across people, tools, times, and places. To illustrate what attention to literate activity offers for understanding writing and learning, we present analyses of learners' embodied actions across an array of semiotic resources including texts, talk, images, and gestures for two different STEM settings: physics and organic chemistry. In addition to foregrounding the wealth and variety of semiotic modalities that mediate students' embodied engagement with disciplinary science, our analyses illuminate the extended histories of semiotic activity that learners continually build as they fashion disciplinary ways of knowing, writing, and becoming.