Current cognitive and sociocognitive models of writing conceptualize writing processes as complex interactions between multidimensional mechanisms that activate a writer's social motivations, psychomotor processes, and cognitive resources in order to engage in writing. These models have been developed through years of empirical research employing a variety of data channels, such as keystroke logging; however, research about mobile writing processes have been understudied. This paper presents a study of mobile writing processes that used keystroke-logging methods in order to expand scholarship of writing processes into the realm of mobile writing. By examining how participants (N = 10) wrote on mobile devices at the keystroke level, as well as combining textual and keystroke analysis to examine context text-message (SMS) composition, this study argues for theoretically framing mobile writing as an embodied performance.