This study traces the claims of a ‘scientization’ and a ‘participatory turn’ in modern governance within the system of temporary policy advisory committees in Norway. It analyzes whether there is evidence of the two claims in these key governance institutions and to what extent these shifts are compatible with each other. As expressions of a participatory turn, a growing emphasis on citizen involvement and transparency in the committee system is searched for. A growing relevance of researchers and of science-based claims in the committees’ reports are taken as indicators of scientization. The longitudinal study shows an overall shift both towards science- and expertise-based governance and towards an increasing openness and public engagement, as well as some variation between policy fields.