ABSTRACT The notion of frictional unemployment failed to grow into a full-fledged theory in the writings of Beveridge, Pigou and Hicks, as these economists were unwilling and/or unable to go beyond the then-prevailing Marshallian approach. Here, first we make explicit the trade organization assumptions underpinning Marshall's equilibrium theory. Next we examine Beveridge's, Pigou's and Hicks' early works on wages and unemployment. Finally, we look at the seminal papers that paved the way for search literature: McCall, Lucas and Prescott, Mortensen and Pissarides. We show that they succeed in providing an unemployment result, because they indeed depart from the Marshallian trade organization. [ABSTRACT FROM AUTHOR]