Twenty years have passed since the publication of Ken Booth’s seminal essay ‘Security and Emancipation’ (1991). It has been 16 years since Ken Booth and Richard Wyn Jones offered the fi rst post-graduate level course on ‘Critical Security Studies (CSS)’ at Aberystwyth University (1995/96).2 Since then, the critical body of work produced by Booth, Wyn Jones, their close collaborators and (by now many) students has come to be known as the Aberystwyth School of CSS. Twenty years on CSS is going strong.3