Standard versions of the sociology of rational practice assume justificationist theories of rationality: all rational beliefs are justified and rational individuals do not believe any non-justified statements. This theory appears to some to offer the possiblity of finding “deeper” insights into social behavior: some actions presented by actors as “rational” can, in fact, be explained as non-justified and, therefore, as mere consequences of prestige and/or power conflicts. When, however, it turns out that no theories can be justified, then all theories are irrational. This leads to relativism. The possibility, that we may profitably construct alternative theories of rationality is, in contrast, raised nearly uniquely by fallibilist theories of rationality. In order to take advantage of this, an alternative to the dominant methodological individualist theory of rational action is needed and possible. According to this alternative, rational action consists of problem-solving within institutional contexts without justification. Such a non-relativist sociology of rational practice can be enlightening and useful. Differing institutional contexts offer differing standards of rationality.