While the subject of interruptions has received considerable attention among organizational researchers, the pervasive presence of information and communication technologies has not been adequately conceptualized. Here we consider the way knowledge workers interact with these technologies. We present fine-grained data that reveal the crucial role of mediated communication in the fragmentation of the working day. These mediated interactions, which are both frequent and short, have been commonly viewed as interruptions — as if the issue is the frequency of these single, isolated events. In contrast, we argue that knowledge workers inhabit an environment where communication technologies are ubiquitous, presenting simultaneous, multiple and ever-present calls on their attention. Such a framing employs a sociomaterial approach which reveals how contemporary knowledge work is itself a complex entanglement of social practices and the materiality of technical artefacts. Our findings show that employees engage in new work strategies as they negotiate the constant connectivity of communication media.