Studies of artistic populations emphasize the role of social security, notably employment insurance, for project-based careers. Analysis of populations of actors and freelance journalists provides an opportunity to question this result, and shows evidence that the social security system does not necessarily shape all project-based careers. In the worlds studied here, individuals' variable relationships to unemployment insurance bring to light several aspects which shed light on the structure of these worlds. It particularly advocates for the importance of taking into account market structures, as they shape the way in which activities are organized in time, with the result that work, rather than employment, emerges as the relevant cognitive category for an individual. Whenever activity comes to resemble entrepreneurship, a person may not be as inclined to define his/her situation as being "unemployed."