Dagenham and Rainham is a constituency represented in the House of Commons of the Parliament of the United Kingdom. It elects one Member of Parliament (MP) by the first past the post system of election. It was first contested in the 2010 general election. Following their review of parliamentary representation in North London, the Boundary Commission for England created the constituency by merging the majority of the former constituencies of Dagenham and Hornchurch. Following a review of ward boundaries a small part of River ward was also transferred from Barking.