The objective of this paper is to investigate the determinants of the adoption of green public procurement (GPP) practices at the local authority level. A conceptual contribution of the paper is an analytical framework, which acknowledges that the adoption of green criteria in tenders should be modelled as a conditionally independent decision from the decision to rely on GPP strategies (guidelines). This approach can help provide novel insights into how various political, organizational, and individual characteristics influence GPP. The paper provides an empirical illustration by concentrating on the role of organizational size. This analysis is based on survey responses from civil servants representing 140 Swedish municipalities. The results are based on the bivariate ordered probit estimator and suggest that large municipalities are more likely to rely on GPP strategies but also less prone to adopt green criteria in tenders when controlling for the presence of such strategies. In large organizations, the centralization of the procurement implies efficiency gains, but it will often be accompanied with longer organizational distances between the procuring and the environmental departments. The paper also highlights the wider implications of the proposed framework, including how future research on GPP practices could approach the role of various political and individual factors.