The Afghan Social Democratic Party, more commonly known as Afghan Mellat is a Pashtun nationalist and a social democratic political party in Afghanistan. The Party was founded on March 8, 1966 by a group of influential bureaucrats associated with the ruling elites. However, it was officially declared on March 27 of that year. Ghulam Mohammad Farhad, an Afghan intellectual served as the first President of the party. Afghan Mellat looks after the interests of the Pashtun ethnic group and has its support only from them. The party favors the ideas of Pashtunization of Afghanistan and a Greater Afghanistan (i.e. it claims the Pashtun-speaking parts of Pakistan for Afghanistan). It has been called ethno fascist by its critics.

Shamsul Huda Shams was elected president of the party in early 1987 following the death of its founder Ghulam Mohammad Farhad. It alleged that some members of the party under a conspiracy refused to accept the electoral results and triggered a split in the party. As a consequence, the Afghan Mellat split into three factions led by
1. Shamsul Huda Shams,
2. Qudratullah Haddad and
3. Mohammad Amin Wakman. Afghanistan’s former finance minister

Since 1995 Anwarul Haq Ahady is the leader of the Wakman faction of the party. Under his leadership, the party toned down its Pashtun nationalist profile and sought support amongst non-Pashtuns. The Wakman branch of the party is recognized by the Afghan government as the "Afghan Mellat Party". The party supported Hamid Karzai in the presidential election and receives support from Karzai. The party has around 10 MPs. The party officially registered themselves in Afghanistan on May 16, 2004.

The Shams Branch under Shams-ul-Huda Shams applied for recognition of his party in 2004, but it was under Ajmal Shams, his son, that it achieved official recognition in May 2007 as "Afghan Mellat Milli Motaraqi Gwand.