The key to understanding the emergence of the independent Irish state lies in the history of Home Rule. This book offers the most comprehensive examination to date of the Irish Parliamentary Party (IPP) at Westminster during the years of John Redmond's chairmanship, 1900-18. The IPP were both the most powerful 'third party' and the most significant parliamentary challengers of the Union in the history of the United Kingdom up until the emergence of the Scottish National Party. The book covers the party's re-unification in 1900 after a decade of division; the dashed hopes of Home Rule in 1912-14; the First World War; 1916 Rising; and concludes with the IPP's electoral annihilation at the hands of Sinn F in in the 1918 general election. Fresh insights into the nature of power and leadership of the party are provided, showing how an inner circle came to dominate the party and how their evolving friendships and alliances impacted upon the efficacy and policy direction of the party. Original research into the collective behaviour of the party both in House of Commons division votes and at question time is provided. This puts the Irish party's behaviour into a British context by comparing their work and activity to the other parties then in the House of Commons. The Irish Parliamentary Party at Westminster, 1900-18 will be of interest to readers of both Irish and British history. It contributes to the history of Ireland's revolutionary decade as well as providing insights that will instruct those interested in modern Irish party politics.