The bloody crackdown on intellectuals in Tiananmen Square on 3 and 4 June 1989 left a lasting impact on Chinese science. The years leading up to the Tiananmen protests had been ones of remarkable openness, with debates breaking out over the relationship between scientific development and political reform. In the repression that followed Tiananmen, dissident scientists were punished, and some fled China. Thousands of Chinese scientists who were overseas in 1989 never returned. While the Chinese government is now aggressively wooing back those scientists—including those who were involved in the protests—some say that the culture of Chinese science has shifted.