New unionism is a term which has been used twice in the history of the labour movement, both times involving moves to broaden the trade union agenda. Ben Tillett was a prominent leader of the London Dock strike of 1889. He formed the Dock, Wharf, Riverside and General Labourers' Union in 1889, which had support from skilled workers. Its 30,000 members won an advance in wages and working conditions.
- They were generally less exclusive than craft unions and attempted to recruit a wide range of workers. To encourage more workers to join, the new unions kept their entrance fees and contributions at a relatively low level. Some new unions, such as the Dockers' Union and the gasworkers developed in the direction of general unionism.
- They recruited unskilled and semi-skilled workers, such as dockers, seamen, gasworkers and general labourers
- At the outset, the new unions were associated with militancy and willingness to take industrial action, unlike the more conciliatory craft unions. Notable strikes associated with the new unions were the London matchgirls strike of 1888 and the London Dock Strike of 1889.
- Many of the new unions had leaders who espoused socialist ideas. Such leaders included Tom Mann, Ben Tillett, Will Thorne and John Burns.
In recent decades the traditional view of the new unions as militant, fighting unions informed by a socialist politics has been modified. Although the new unions sponsored many large strikes in their early years, most, in fact, favoured conciliation and accommodation with the employers. Similarly, although new union leaders espoused socialism, it was often of a moderate kind.
The most prominent new unions were:
- Dockers' Union
- National Union of Dock Labourers
- Gasworkers Union
- National Sailors' and Firemen's Union
The second time the term new unionism was used covers a period from the late 1980s until the present day. In 1988, US labour relations academic Charles Heckscher published "The New Unionism: Employee Involvement in the Changing Corporation" and this became one of a series of influential papers which encouraged the union movement to reconsider questions of industrial democracy. The UK Trades Union Congress ran an ambitious new unionism project from 1997 to 2003, seeking to apply a dual strategy of organizing and partnership in an attempt to reinvigorate the union movement. This period saw an end to the decline in union membership, but the net effect is still subject to debate within the movement. 
More recently unions such as the Service Employees International Union (SEIU) in North America and the Public Services Association (PSA) in New Zealand have combined innovative organizing and partnership combinations with notable success, leading to large and sustained membership gains (about 50% in each case) and increased influence and activism at workplace level.
An international new unionism network was launched in 2007 to bring unionists and labour supporters together around developing and applying these principles. The network provides fora and other resources for those interested in implementing the agenda.