["Journal for the Scientific Study of Religion, Volume 65, Issue 1, Page 123-135, March 2026. ", "\nABSTRACT\nThis study aims to determine whether different groups of nondenominational Protestants more closely resemble one of the three most widely recognized denominational families within American Protestantism: Mainline Protestants, Evangelical Protestants, and Black Protestants. Steensland et al.’s and Gaghan and Eagle's RELTRAD coding schemes are modified to include contested categories of nondenoms that are disaggregated by race and church attendance. Findings from the 2000–2022 General Social Surveys indicate that the coding schemes capture similar variation between Black nondenoms and members of historically Black Protestant denominational families. However, non‐Black nondenoms who attend less than once a year significantly differ from followers of historically Mainline Protestant denominations, and non‐Black nondenoms who attend more than once per month report more conservative religious sensibilities as well as political and social attitudes than members of historically Evangelical Protestant traditions. Such findings attest to both strengths and limitations within the RELTRAD taxonomies under analysis. Consequently, further research is needed to inform durable decisions regarding the treatment of data for non‐Black nondenoms in RELTRAD. Suggestions for improvement are offered—including what now appears to be arbitrary cut‐off points used to distinguish between nondenominational Protestants—in helping scholars produce more accurate statistical estimates for Protestants who do not affiliate with established traditions.\n"]