The requirement that scientific theories include both abstract concepts and concrete implications, and that the two be logically connected, has been treated rather casually by sociologists. Traditionally, sociological theorists have focused on abstractions with loose and ill-defined implications about matters of fact. More recently, some sociological formulations have shifted to the opposite extreme, stating only connections between measures without any attempt to make more abstract claims. Either of these modes of theory construction is costly, sacrificing either the clarity of empirical implications or the integrating potential of abstract concepts. Although the literature of the philosophy of science has provided us with terms for referring to the gap between abstract conceptions and concrete events— rules of correspondence, epistemic correlations, operational definitions, and indicators of abstract dimensions —these terms do little more than remind us that the gap is there. They do not provide clear guidelines for bridging the gap and suggest no criteria for determining the adequacy of the more or less arbitrarily devised connections between abstract and empirical levels. Clearly, the empirical testing of abstract theories must remain somewhat loose until 230some strategies for dealing with this problem are devised. To the degree that rules of correspondence are weak and subject to distorting errors, deductions about matters of fact must be regarded as uncertain and possibly misleading.