Muhammadiyah (Arabic: محمدية, followers of Muhammad. full name: Persyarikatan Muhammadiyah) is a major Islamic non-governmental organization in Indonesia. The organization was founded in 1912 by Ahmad Dahlan in the city of Yogyakarta as a reformist socioreligious movement, advocating ijtihad - individual interpretation of Qur'an and sunnah, as opposed to taqlid - the acceptance of the traditional interpretations propounded by the ulama. Since its establishment, Muhammadiyah has adopted a reformist platform mixing religious and secular education, primarily as a way to promote the upward mobility of Muslims toward a 'modern' community and to purify Indonesian Islam of local syncretic practices via a quasi-Wahhabi movement. It continues to support local culture and promote religious tolerance in Indonesia, while a few of its higher education institutions are attended mostly by non-muslims, especially in East Nusa Tenggara and Papua provinces. The group also runs a large chain of charity hospitals, and operated 128 universities as of the late 1990s.
At the moment, Muhammadiyah is the second largest Islamic organization in Indonesia with 29 million members. Although Muhammadiyah leaders and members are often actively involved in shaping the politics in Indonesia, Muhammadiyah is not a political party. It has devoted itself to social and educational activities.
On November 18, 1912, Ahmad Dahlan— a court official of the kraton of Yogyakarta and an educated Muslim scholar from Mecca—established Muhammadiyah in Yogyakarta. There were a number of motives behind the establishment of this movement. Among the important ones are the backwardness of Muslim society and the penetration of Christianity. Ahmad Dahlan, much influenced by Egyptian reformist Muhammad 'Abduh, considered modernization and purification of religion from syncretic practices were very vital in reforming this religion. Therefore, since its beginning Muhammadiyah has been very concerned with maintaining tawhid, and refining monotheism in society.
From 1913 to 1918, Muhammadiyah established five Islamic Schools. In 1919 an Islamic high school, Hooge School Muhammadiyah was established. In establishing schools, Muhammadiyah received significant help from the Boedi Oetomo, an important nationalist movement in Indonesia in the first half of the twentieth century, such as in the form of providing teachers. Muhammadiyah has generally avoided politics. Unlike its traditionalist counterpart, the Nahdatul Ulama, it never formed a political party. Since its establishment, it has devoted itself to educational and social activities.
In 1925, two years after the death of Dahlan, Muhammadiyah only has 4,000 members, even has built 55 schools and two clinics in Surabaya and Yogyakarta. After Abdul Karim Amrullah introduced the organisation to Minangkabau dynamic Moslem community, Muhammadiyah developed rapidly. In 1938, organisation claimed has 250,000 members, managed the 834 moques, 31 libraries, 1,774 schools, and 7,630 ulema. The Minangkabau Merchants spread organization to the entire of Indonesia.
During the 1965-66 political turbulence and violence, Muhammadiyah declared the extermination of the "Gestapu/PKI" (the 30 September Movement and the Indonesian Communist Party) constituted Holy War, a view endorsed by other Islamic groups. (see also: Indonesian killings of 1965-66). During the 1998 "Indonesian reformation", some parts of Muhammadiyah urged the leadership to form a party. Therefore, they - including Muhammadiyah chairman, Amien Rais, founded the National Mandate Party. Although gaining large support from Muhammadiyah members, this party has no official relationship with Muhammadiyah. The leader of Muhammadiyah says the members of his organisation are free to align themselves with political parties of their choosing provided such parties have shared values with Muhammadiyah.
Today, with 29 million members Muhammadiyah is the second largest Muslim organization in Indonesia, after Nahdlatul Ulama.
The central doctrine of Muhammadiyah is Sunni Islam. However, the main focus of the Muhammadiyah movement is to heighten people's sense of moral responsibility, purifying their faith to true Islam. It emphasizes the authority of the Qur'an and the Hadiths as supreme Islamic law that serves as the legitimate basis of the interpretation of religious belief and practices, in contrast to traditional practices where shariah law invested in religious school by ulema.
Muhammadiyah strongly opposes syncretism, where Islam in Indonesia has coalesced with animism (spirit worship) and with Hindu-Buddhist values that were spread among the villagers, including the upper classes, from the pre-Islamic period. Furthermore, Muhammadiyah opposes the tradition of Sufism that allows Sufi leader (shaykh) as the formal authority of Muslims.
As of 2006, it is said to have "veered sharply toward a more conservative brand of Islam" under the leadership of Din Syamsuddin the head of the Indonesian Ulema Council.
Muhammadiyah is noted as a Muslim reformists organization. Its main activities are religion and education. It has built Islamic schools in modern forms, aside from traditional pesantren. Some of its schools are also open to non-Muslims. Currently there are around 5,754 schools owned by Muhammadiyah.
It has also functioned as a charitable organization. Today it owns several hundred non-profit medical clinics and hospitals across Indonesia. Recently it has been active in campaigning about the danger of bird flu in Indonesia.
The national headquarters was originally in Yogyakarta. However, by 1970 the committees dealing with education, economics, health and social welfare had been relocated to the national capital, Jakarta.
Muhammadiyah is supported by several autonomous organizations:Aisyiyah ( Women )
Pemuda Muhammadiyah ( Youth )
Nasyiatul Aisyiyah ( Young Women ) (http://nasyiah.or.id)
Ikatan Pelajar Muhammadiyah ( Student association ) 
Ikatan Mahasiswa Muhammadiyah (College student ) 
Tapak Suci Putra Muhammadiyah (Pencak Silat)
Hisbul Wathan ( Scouting ).
The central committee structure consists of five advisors, a chairman, a vice chairman, a secretary general and some deputies, a treasurer and some deputies, as well as several deputies of chairman.
Muhammadiyah organisation has a number of universities which are spread out in several provinces of Indonesia, such as:Ahmad Dahlan University of Yogyakarta
Muhammadiyah University of Malang
Muhammadiyah University of Yogyakarta
Muhammadiyah University of Surakarta
Muhammadiyah University of Purwokerto
Muhammadiyah University of Makassar Unismuh
Muhammadiyah University of Magelang UMMGL
Muhammadiyah University of Semarang
Muhammadiyah University of Metro, Indonesia
Muhammadiyah University of Palembang
Muhammadiyah University of Bengkulu
Muhammadiyah University of West Sumatra
Muhammadiyah University of North Sumatra
Muhammadiyah University of Aceh
Muhammadiyah University of Cirebon
Muhammadiyah University of Bekasi
Muhammadiyah University of Purworejo
Muhammadiyah University of Surabaya
Muhammadiyah University of Sidoarjo
Muhammadiyah University of Gresik
Muhammadiyah University of Jember
Muhammadiyah University of Kupang
Muhammadiyah University of Ternate
Muhammadiyah University of Gorontalo
Muhammadiyah University of Jakarta
Muhammadiyah University of Prof. Hamka
Muhammadiyah University of Parepare
Muhammadiyah University of Sukabumi
Muhammadiyah University of Ponorogo
Muhammadiyah University of Pontianak
Muhammadiyah University of Sorong, Papua