The present thesis sets out to provide an understanding of how European integration affects NPs in the EU and their relationship to the executive. The main objective of the empirical analysis is to investigate how parliamentary control of government serves EU scrutiny between 1999 and 2011. The case study, which focuses on the Luxembourgish Chamber of Deputies allows for a test of changes in governmental discretion on three parliamentary control dimensions in different domestic and European contexts of coalition governments and European Treaties. The theoretical framework for interpreting the impact of the EU on NPs and executive-legislative relations is a combination of the larger concept of top-down Europeanisation with the principal agent approach. The emphasis is on the EU as an external force being central in the adaptation of parliamentary control of government, while taking into account the particularity of parliament as a principal. Based on the delegation argument, we generate hypotheses about the evolution of parliamentary democracy under the condition of a highly decentralised committee system, multiple committee membership, high party cohesion and majority government. Our empirical findings run counter to the predictions of the deparliamentarisation hypothesis. This owes to the fact that we investigate parliamentary control of government in a most inclusive perspective. Rather than weakened, this study considers the Luxembourgish parliament strengthened not least by the opportunities offered by the Lisbon Treaty. In complicity, it backs up a government which has lost on discretion at EU level.