Drawing on empirical research in a number of academic disciplines, and
on contrasting doctoral research training in laboratory sciences with
that in social sciences, the article examines the notion of 'critical
mass', which has informed recent policy and debate about research tra
ining in the UK. Based on a critique of the Harris Review of Postgradu
ate Education, it is argued that such policy perspectives are insensit
ive to the fundamental differences between academic cultures and modes
of organisation in different academic disciplines.