Through his early studies of the character of adult schools and community colleges in California, Burton Clark launched a set of ideas, sociological and educational, that served as baseline concepts in the study and practice of American higher education. His book The Open Door College ranks among the classic accounts of a type of organisation – the public two-year college – which came to prominence throughout the United States in the post-war period. Its consideration of the roles played by such institutions in the larger education structure and society has been at the centre of international, theoretical and empirical debates for half a century. Foremost among its arguments was the cooling-out function, a conception that enjoyed wide circulation over many decades. Rather less attention has been paid to its analysis of organisational determinacy and the special problems of institutions that straddle secondary and higher education. These are the mass enterprises that do much of the dirty work of higher education. Unlike in the Clark corpus, they do not always receive the seriousness of scholarly treatment accorded to other kinds of educational organisation.