Career paths may often appear and be described as conscious and forward-looking, depicting meritocracy and achievements as the foundation for a person's career development. This applies not least to academic careers, where the importance of hard work, strategic choices, innovative thinking and research breakthroughs can be attributed great significance. At the same time, there is often a certain amount of luck and happenstance in how careers develop, which interacts with individuals' work and strategic choices. The aim of this article is to investigate what significance luck and happenstance are ascribed in descriptions of academic career trajectories and how this can be understood in relation to practical and economic conditions as well as norms and expectations within the academic context. The theoretical framework is based on the concepts of serendipity and agency, and the empirical material consists of qualitative interviews with alumni from multidisciplinary graduate schools in Sweden. The results show how the interviewed alumni talked about luck and happenstance in relation to various aspects of and stages in their academic careers, at the same time as they connected the ability to take advantage of such fortunate circumstances to their aspirations and the hard work they had done, to existing conditions, e.g., labour markets and family life as well as to norms and expectations within the academic communities.