In 1979, less than 30% of full-time university students in Canada worked for pay during the academic year. By the mid-2000s, this had risen to 45%. This trend to increasing work among full-time students is also evident in other countries, and may be a concern if it reduces students' investment in human capital during their studies. I find that, controlling for the demographic characteristics of the student population, the only economic variable that explains a substantial portion of the increase in students' work is higher tuition fees.