Tarrance served as the Special Assistant to the Director of the 1970 U.S. Census and was also named by the Secretary of Commerce as Co-Chairman of the Federal Advisory Committee on the adjustment of the 1990 Census. Earlier, he served as the Director of Research for the Republican National Committee and was an officer of the 1968 Republican National Convention. Tarrance has been selected as a member of "Who's Who in America" every year since 1990, and "Who's Who in the World" since 2008. Tarrance is also a co-founder of the Raleigh Tavern Philosophical Society of Texas.