The Protestant Reformation swept across Central Europe in the early-sixteenth century, leaving cities divided into Evangelical and Catholic camps as some instituted reforms and others remained loyal to the Roman Church. In offering a new explanation of the Reformation, we develop a theory that identifies ideologically mobilized students as bridge actors--that is, agents of religious contention who helped concatenate incidents of local insurgency into a loosely organized Evangelical movement by bridging structural holes. Building on existing literature, we offer a novel way to measure the influence of contending religious movements through university enrollments; we propose that the institution of reform can be partially explained by the varying degree of exposure that cities had to Evangelical activist and Catholic loyalist university students. Based on statistical analysis of a novel dataset comprising cities in the Holy Roman Empire with a population of 2,000 or more from 1523 to 1545, we find support for the role of university students as bridge actors linking critical communities at universities to arenas of urban contention. The greater a city's exposure to heterodox ideology through city-to-university ties, the greater its odds of instituting the Reformation. (Contains 1 figure, 5 tables, and 5 notes.)