Connolly’s legacy in Ireland is mainly due to his contribution to the republican cause; his legacy as a socialist has been claimed by a variety of left-wing and left-republican groups, and he is also associated with the Labour Party which he founded. Connolly was among the few European members of the Second International who opposed, outright, World War I. This put him at odds with most of the socialist leaders of Europe. There is a statue of James Connolly in Dublin, outside Liberty Hall, the offices of the SIPTU trade union. Another statue of Connolly stands in Union Park, Chicago near the offices of the UE union. There is a bust of Connolly in Troy, New York, in the park behind the statue of Uncle Sam.

He was influenced by and heavily involved with the radical Industrial Workers of the World labour union, and envisaged socialism as Industrial Union control of production. Also he envisioned the IWW forming their own political party that would bring together the feuding socialist groups such as the Socialist Labor Party of America and the Socialist Party of America. Likewise, he envisaged independent Ireland as a socialist republic. His connection and views on Revolutionary Unionism and Syndicalism have raised debate on if his image for a workers republic would be one of State or Grassroots socialism. For a time he was involved with De Leonism and the Second International until he later broke with both.