Karlijn Massar is an associate professor in the Section of Applied Social Psychology, in the Department of Work and Social Psychology.

Since 2019, she is also Adjunct Professor at the Faculty of Psychology, Airlangga Universitas, Surabaya, Indonesia.

Her research interests include: health inequalities and the role of psychological capital to reduce them; jealousy; intrasexual competition; evolutionary psychology; individual differences in personality traits; maternal health (in Sub-Sahara Africa), applying evolutionary psychology to health issues; relationships.

In 2017, Karlijn obtained a grant from The Netherlands Organisation for Health Research and Development (ZonMw) to develop, implement and evaluate an intervention aimed at increasing healthy behaviors among lower SEP-employees: "Future Positive".