The growth of the college wage premium decelerated after the 1980s and even more so since 2000. The deceleration challenges the skill-biased technological change theory which is the most powerful explanation for the rapid growth in the 1980s. In this research, I build a model that captures the progress of skill-biased technologies, automation and the mean quality change of high-skilled workers to explain this deceleration. The novel feature of the model is that the supply of high-skilled workers endogenously depends on the progress of technologies and other shocks. I show the change in progress basis of skill-biased technologies is the primary reason that leads to the deceleration relative to the change in progress speed of skill-biased technologies and the progress of automation. This result suggests the deceleration of college wage premium growth is an inevitable outcome of skill-biased technological change while both demand reversal and polarization have only moderate explanatory power. About the direct mechanism of the deceleration, I find that the faster decline in the mean quality of high-skilled workers followed by a greater offset of skill-biased technological change's positive impact on college wage premium growth due to increase in the progress basis of skill-biased technologies is the primary direct mechanism.