The Salvation Army (TSA) is a Protestant Christian church and an international charitable organization headquartered in London, England that is aligned with the Wesleyan-Holiness movement. The organisation reports a worldwide membership of over 1.7 million, comprising soldiers, officers and adherents collectively known as Salvationists. Its founders sought to bring salvation to the poor, destitute, and hungry by meeting both their "physical and spiritual needs". It is present in 133 countries, running charity shops, operating shelters for the homeless and disaster relief, and humanitarian aid to developing countries.

The theology of the Salvation Army is derived from Methodism, although it is distinctive in institution and practice. A distinctive characteristic of the Salvation Army is its use of titles derived from military ranks, such as "lieutenant" or "major". It does not celebrate the rites of Baptism and Holy Communion. However, the Army's doctrine is aligned with the Wesleyan–Arminian tradition, particularly the holiness movement. The Army's purposes are "the advancement of the Christian religion... of education, the relief of poverty, and other charitable objects beneficial to society or the community of mankind as a whole".

The Army was founded in 1865 in London by one-time Methodist preacher William Booth and his wife Catherine as the East London Christian Mission, and can trace its origins to the Blind Beggar tavern. In 1878, Booth reorganised the mission, becoming its first general and introducing the military structure which has been retained as a matter of tradition. Its highest priority is its Christian principles. The current international leader of The Salvation Army and chief executive officer (CEO) is General Brian Peddle, who was elected by the High Council of The Salvation Army on 3 August 2018.

In 2011, Charity Watch rated the Salvation Army an "A−" to an "A", indicating a high level of financial efficiency and organisational transparency. The Salvation Army has received an A- rating from the American Institute of Philanthropy.

The Salvation Army is one of the world's largest providers of social aid, with expenditures including operating costs of $2.6 billion in 2004, helping more than 32 million people in the U.S. alone. In addition to community centres and disaster relief, the organisation works in refugee camps, especially among displaced people in Africa. In the United Kingdom, the Salvation Army is no longer the largest non-governmental provider of social services; however, it still provides a significant service to people in need. The Salvation Army is the fourth largest charity in the United States, with private donations in excess of $2 billion in 2022, and is a member of the American organisation Christian Churches Together.