["Sociological Forum, EarlyView. ", "\nUsing age‐period‐cohort modeling (APC), scholars suggest that the profound increase in Americans’ acceptance of same‐sex relations is mainly explained by “period” effects, in which people have become more tolerant of same‐sex relations over time regardless of their age or birth cohort. To further explain the patterns of attitude changes, this research situates period effects in the specific sociohistorical boundaries unique to the development of same‐sex issues in the United States. This contextualization of period effects also sheds light on how and why attitudes have shifted at different paces for various sociodemographic groups. Using data from the 1973 to 2018 General Social Survey, the ordered logistical models reveal that significant period effects have emerged only after the height of the AIDS Epidemic. The surge of public acceptance after this period was accompanied by heightened demographic and cultural polarization, with changes in attitudes for black and for politically and religiously conservative individuals shifting at a much slower pace than their nonblack and less conservative counterparts. Such a polarization in attitudes reflects the ever‐changing association between sociodemographic characteristics and mainstream cultural beliefs about same‐sex relations over time.\n"]