This report synthesizes the findings from a research project on “Parliamentary strengthening and the Paris Principles”. The aim of the research project has been to generate better evidence about parliamentary strengthening, in order to inform decisions about whether and how Development Partners can best support parliaments in developing countries. The project – a collaboration between ODI and the Parliamentary Centre, with funding provided by DFID and CIDA – has involved four country case studies; Cambodia, Ghana, Tanzania and Uganda. The vantage point taken for the analysis is that of the Paris Principles on Aid Effectiveness.