The country gained independence from the Portuguese in 1975 but had only one legal party, the Movement for the Liberation of São Tomé and Príncipe – Social Democratic Party (MLSTP-PSD).
In 1990 the constitution was changed following a referendum and for the first time it allowed for multi-party democratic elections.
Those first multi-party elections took place on 20th January 1991 where the Democratic Convergence Party – Reflection Group (PCD-GR) took 33 of the 55 seats in the National Assembly. On 3rd March presidential elections were held, but there was only one candidate, Miguel Trovoada, who was elected unopposed.
President Trovoada was re-elected in 1996 with 52.6% of the vote.
In 1994 the former single party the Movement for the Liberation of São Tomé and Príncipe – Social Democratic Party (MLSTP-PSD) came back to prominence, winning 27 of the 55 seats and they increased their tally in 1998, taking 28 seats.
In 2001 President Trovoada was not permitted to stand, having completed two consecutive terms and the presidential election was won by Fradique de Menezes of the Independent Democratic Action (ADI). He won again in 2006 with 60.6% of the vote and cannot stand in 2011, having completed two terms.
In 2002, the MLSTP-PSD was the largest party once more with 24 seats, but in 2006 they dropped four seats and came second to an alliance of the PCD-GR and the Force for Change Democratic Movement – Liberal Party (MDFM – PL).
By 2010 the alliance had broken up and the two parties stood independently. The Independent Democratic Action (ADI) won the most seats, 26, with the MLSTP-PSD coming second with 21 seats. The PCD-GR was third with seven seats and the MDFM – PL was virtually wiped out, taking just one seat.
During the period described above, there were several military coups. In August 1995 there was a bloodless coup after which, following Angolan mediation, the president and government were returned to power.
Again there was a brief coup by young army officers in 1996 but normality was restored in days. On 16th July 2003 a military coup was held as the president was out of the country, but again normalcy was restored within eight days. A further coup plot was announced in February 2009, with a political leader and thirty others being arrested.
The President is elected for a five year term and is eligible to stand for a second term.
There is a unicameral National Assembly consisting of 55 seats with members serving four year terms.
The Transparency International Corruption Perceptions Index (CPI) 2016 places São Tomé and Príncipe at joint 62nd out of 176 countries with a CPI 2016 score of 46 (where 100 is least corrupt).