Three approaches to innovation in the public sector in the post war period are identified and analysed for their implications for policy-makers, managers and citizens. Various relationships are identified between innovation and improvement in public services. The traditional bias of the literature that innovation is necessarily functional is undermined. Important lessons for policy, practice and research include the need to develop an understanding of innovation which is not over-reliant on the private sector manufacturing literature but reflects the distinctive contexts and purposes of the public sector.