This paper offers a critique of existing models of continuing professional development (CPD) courses for science teachers in the light of recent thinking about the nature of the subject (in particular, the arguments associated with "post-normal science") and the challenges presented by the teaching of controversial socio-scientific issues (especially topics like biotechnology and genetic modification). An analysis of the outcomes and limitations of an "up-date/top-down" kind of CPD is used to argue that future forms of effective CPD must involve teachers in reflecting on the scientific, the social and the pedagogical dimensions to "new science," and the relationships between them in the interests of improved classroom learning. (Contains 1 figure, 1 table, and 1 note.)