Moqtada al-Sadr is a Shi'ite political and militia leader in Iraq, who has been active in Islamic sectarian conflict and internal warfare, but is increasingly involved in the government process. His political organization is called the Mahdi Army; its military wing is variously called the Mahdi Army or the Jaish al-Mahdi (JAM). It has not been a political party in the classic sense, but rather backs candidates.
Moqtada had been considered too fiery and young while his elders were alive. When his father, Sadiq al-Sadr and two sons were shot in 1999, probably on orders of Saddam, a network of schools and charities built by his family. But winning the allegiance of the elder Sadr's followers was not guaranteed.  The ICG reported he was "by no means his father's natural heir." Muqtada's decision to form a government in the waning days of the Ba'ath Party did little to sway the critics. "Many Shiites were shocked" by the move, a close associate of the Sadrist movement told ICG in January 2006. "They felt that he was too young, that he was nothing but a za'tut," or ignorant child.
He fought with the major Shi'a party, SCIRI (now ISCI), and the most influential Shiite leader was Grand Ayatollah Ali al-Sistani, brokered the agreement between SCIRI and the Mahdi Army.  An additional middle-class Shi'a party has emerged, the Islamic Dawa Party of Prime Minister of Iraq Nouri al-Maliki. According to Vali Nasr at the Council on Foreign Relations, "by 2008 Muqtada had expanded his movement from being essentially a Baghdad street force into 'a major Shiite movement, with parliamentary presence, political presence, as well as now a very large military presence on the street.' Nasr says Sadr 'now represents one of the two most important Shia blocs in the country.'"
Positioning within Shi'a Iraq
He and his relatives have been associated with the lower classes of Iraqi Shi'as, and have taken a populist role, sometimes called class struggle. Early in his movement's progression, it began providing social services; the resemblance to Hezbollah's building a base as a shadow government is not coincidental.
There are several theories of authority in Shi'a Islam. Wilayat al-faqih, which places jurists as the supreme political authority, is the basis for the Iranian theocracy, but has not been the position of the leading Iraqi Shi'a clerics. Moqtada was initially endorsed, in 2004, by Qom-based Iraqi-born cleric Kazim al-Husseini al-Haeri reportedly issued a religious edict in early April that was distributed among Shia clerics in Iraq that calls on them "to seize the first possible opportunity to fill the power vacuum in the administration of Iraqi cities." "We hereby inform you that Mr. Muqtada al-Sadr is our deputy and representative in all fatwa affairs," Haeri's decree adds. "His position is my position."
American civil viceroy L. Paul Bremer, was concerned, in early March, with Muqtada al-Sadr in Najaf, who was becoming increasingly militant in reaching for power as his Shi'ite rival, Sistani, fought for Shi'a power in the constitutional process. He took effective control of the Kufa mosque and preached violence from there.
Complicating the situation with Najaf, [Kufa, and other southern areas were that they were under operational control of the Polish division commander, with subordinate Bulgarian, Central American, Spanish and Ukrainian units, each with different rules of engagement. The Spanish contingent was the one most immediately affected. Bremer asked LTG Ricardo Sanchez to plan a way to deal with the situation there.  Bremer ordered Sanchez on March 27, to close al-Sadr's newspaper, Hawza, for 60 days; this took place without violence but with much protest.
In April 2004, the Coalition Provisional Authority (CPA) announced that an Iraqi judge has issued an arrest warrant for him, in connection with the 10 April 2003 murder of Shi'ite Grand Ayatollah Abdul-Majid al-Khoei.
Al-Haeri, however, later disavowed the relationship. Al-Haeri once had a close relationship with the Shia Al-Da'wah al-Islamiyah party, but split with the group because al-Haeri was excessively pro-Iranian and called for the party to respect the guidance of Iranian Supreme Leader Ayatollah Ali Khamenei, Beirut's "Al-Mustaqbal" reported on 24 April.
Since then, the 68-year-old al-Haeri renounced his relationship with al-Sadr. "Mr. al-Sadr used to be our representative...but that was on condition of obedience to and coordination with our office in Al-Najaf," al-Haeri said in comments posted on his website, AP reported on 5 September. Al-Sadr "does not coordinate with our office, so his agency became void," according to the website, which added that al-Sadr "does not seek our advice in his stances, so we cannot endorse what he does." According to a 5 September report in "The New York Times," al-Haeri withdrew his support for al-Sadr after Ayatollah Ali al-Sistani informed senior clerics in Qom that the Imam al-Mahdi Army caused some of the battle damage at the Imam Ali shrine in Al-Najaf.
Operations in Najaf
On April 3, special operations forces arrested one of al-Sadr's assistants, and al-Sadr responded with a call for arms. By the 4th, a 1st Cavalry Division platoon was ambushed, unaware that the arrest had taken place or that high vigilance was indicated; Sanchez called this a breakdown in communications at the division commander level; the 1st Cav was taking over from the 1st Armored Division (U.S.).
Al-Sadr's attacks spread across southern Iraq, and he took control of the capitals of Basra, Al Kut, Nasiriyah, and Basra. They fought British and Dutch forces in Basra.  In Kufa, al-Sadr put his base in the Great Mosque, creating the extremely difficult problem of attacking a religious sanctuary in a war where religion was a major factor. 
While he is a religious activist from a family of clerics, he did not complete clerical studies before his political involvement.
But in December 2007 he issued a decree calling on followers to devote more time to religious endeavors, and announced his intention to enroll in the conservative Al-Hawzah, or seminary, in Najaf. Babak Rahimi, an expert in Shiite politics and former fellow at the United States Institute of Peace, writes that Sadr's religious move indicate "a major change in the movement's structure that could have serious repercussions for the future of Iraq." Sadr's motivation may also be to "reinforce his Iraqi identity," Rahimi adds, although the cleric's whereabouts in mid-2008 may complicate that effort: Most experts believe he took his religious studies to the Iranian city of Qom—raising questions about Iran's influence on the cleric and his militia.
He entered the government in 2005, and his bloc won 32 of 275 parliamentary seats in the December 2005 national elections. Again remembering that his positioning involves class as well as religious and ethnic identity, it provided representation for Shi'ites that felt disenfranchised within their kin group. Vali Nasr said it made him "a kingmaker," as he had a role in getting al-Maliki into the Prime Minister post; he also put allies into political posts, emphasizing the social service ministries and the provincial governorates.
In a January 2006 interview with Al Arabiya news channel, Sadr explained his political coming of age this way: "The Sadrist movement first resorted to peaceful resistance, then to armed resistance, and finally to political resistance."
While he was at religious studies, some of his more radical followers broke away and continued fighting, while 200 political allies split from his movement in March 2009. They formed a group called Shura al-Ulla'ama, or Clerics Advisory. According to Sheikh Youseff al-Nassiry, a leader of the breakaway movement, said in an interview that "the group, the aims to perform social services like those offered by the Sadr movement and to become a political force, but it wants to distance itself from the Sadr movement's violent elements. The group, which is setting up its main office in Baghdad's Jadriya area plans to run candidates in national elections to be held as soon as December. They met for the first time on March 21 at Baghdad's Babylon Hotel, along with Zuhair Chalabi, head of the government's reconciliation committee.
He visited Turkey in May 2009 and had regional security discussions with Prime Minister of Turkey Tayyip Recep Erdogan and President of Turkey Abdullah Gul. The focus was on the disputed area of Kirkuk, involving ethnic conflict between Shi’a Turkmen, Kurds and Sunni Arabs. 
After Saddam's ouster in 2003, he was treated strictly as an insurgent, but, as time went on, there were informal contacts.
In May 2007, four factions of Jaish al-Mahdi were fighting one another in a Baghdad neighborhood. Ricks quoted Kilcullen as saying that the U.S. command sent a message to "JAM Central" in Najaf to deal with it, and "because we treated them as the authority, they cleaned it up."
From the U.S. perspective, he was a threat, but a threat that would not go away. GEN Ray Odierno said, in January 2008, "we are now meeting with them, for the first time. He's clearly moving more to a humanitarian approach." American officials started calling him "the honorable", and GEN David Petraeus, in February, used the honorific "al-Sayyid", referring to him as a descendant of the Prophet. 
- Iraq's Muqtada al-Sadr: Spoiler or Stabilizer, International Crisis Group, 11 July 2006, Middle East Report N°55
- Greg Bruno (16 May 2008), Backgrounder: Muqtada al-Sadr, Council on Foreign Relations
- Sharon Otterman (1 September 2004), Backgrounder: IRAQ: Grand Ayatollah Ali al-Sistani, Council on Foreign Relations
- Muqtada al-Sadr, Globalsecurity
- L. Paul "Jerry" Bremer with Malcolm McDonnell (2006), My Year in Iraq: The Struggle to Build a Future of Hope, Simon & Schuster, ISBN 9780743273893, pp. 122-124
- Patrick Cockburn (11 April 2008), "Warlord: The rise of Muqtada al-Sadr", Independent (U.K.)
- Bremer, My Year in Iraq, p. 312
- Ricardo S. Sanchez with Donald T. Phillips (2008), Wiser in Battle: a Soldier's Story, HarperCollins, ISBN 9780061562426, pp. 335-336
- Ron E. Hassner (Spring 2006), "Fighting Insurgency on Sacred Ground", The Washington Quarterly, p. 155
- Gina Chon (30 March 2009), "Iraq Hopes Grow on Split in Sadr Body, Amnesties", Wall Street Journal
- Babak Rahimi (May 26, 2009), "Iraq’s Muqtada al-Sadr Seeks Regional Influence with Visit to Ankara", Terrorism Monitor, Jamestown Foundation
- Thomas Ricks (2009), THE GAMBLE: General David Petraeus and the American Military Adventure in Iraq, 2006-2008, Penguin, ISBN 987-1594201974, p. 267