We develop a conceptual model of a knowledge work activity system, based on a study of the relative time spent on tasks amongst academics at work. Through a critical discussion of tasks as an object of study, and not as a unit of analysis, we apply the epistemological lens of the Systemic-structural Theory of Activity (SSTA), a branch of Activity Theory, to theorize knowledge work activity. Knowledge work is a recognized facet of competent organization and competitive positioning. Situated as knowledge workers are, on the cusp of the socio-technical and the socio-cultural milieu, we argue that an opportunity exists for information systems researchers to reveal how both 'task' and 'activity', as objects of study, are instrumental in clearing misunderstanding as to what constitutes knowledge work. The relationship between terms such as task', 'action', and 'activity' are integral from the perspective of task analysis, and this underscores the review of recent research literature in Activity Theory. We contend that, through SSTA, both theoretical and practical interpretation of taskholder behaviour oopens a way forward from which to gauge the moderating influence of task features on the knowledge work of individuals along with the mediating influence of socio-technical or socio-cultural artefacts.