Rolf Jansen's research focuses on ground- and space-based ultraviolet–mid-infrared broad- and narrow-band surface photometry and spectroscopy of relatively nearby galaxies. His aim is to study their content and to unravel their formation and assembly histories as a function of galaxy type, luminosity, and cosmic environment, and to track the hierarchical assembly of galaxies over time to the present. He served as instrument scientist for a NASA concept study into a next-generation UV--optical space telescope, provided input and support to the James Webb Space Telescope project, and is currently a member of a Nancy Grace Roman Space Telescope (formerly WFIRST) Science Investigation Team. He also provides computer and astronomical data analysis support within the SESE Cosmology Initiative.