The increasing opportunities created for adults by on-line distance universities raise important issues about the payoff to such education. This study uses a unique set of survey data gathered by the Open University of Catalonia (UOC) in 2009 to estimate the earnings gains of the 2000-2003 cohorts of UOC students in six programmes of study over an average six-year time frame between entering and one year after leaving their studies. It compares their gains with the earnings gains of comparable full-time workers in the Spanish labour force by age, education level, and gender. The results show that those who studied in UOC's two-year second-cycle degree programmes had positive relative earnings gains but those in three-year first-cycle degree programmes did not. The study further discusses why adult learners might nevertheless study toward degrees for which payoffs appear low. (Contains 7 tables.)