President: Michael Sata
Mr Sata came to power in elections in 2011
Michael Sata, of the Patriotic Front, won the presidency in elections in September 2011, unseating the Movement for Multi-party Democracy which had held power for the previous 20 years.
The elections were marred by outbursts of violence which left two people dead, but the new president was sworn in within hours of the election result being declared.
Mr Sata became president on his fourth try, having previously been a member of the governing party. He vowed to transform the fortunes of Zambia, which is one of the world's largest producers of copper.
He replaced Rupiah Banda, whose Movement for Multi-party Democracy ruled since Frederick Chiluba unseated independence leader Kenneth Kaunda in the first democratic elections in 1991.
Although apparently showing signs of his age when he was elected at 74, Mr Sata tapped into the grievances of the youth and the urban poor who feel left out of the impressive economic growth in Africa's biggest copper producing nation.
The Patriotic Front has vowed to bring back a 25% windfall tax on mining revenues that Banda's government abolished in 2009.
The increase in copper prices since then - from around $3,000 a tonne to almost $10,000 - and the friendly tax regime have drawn a rush of foreign and investment to Zambia, particularly from China.
Mr Sata's critics fear that this strong-willed firebrand, who has openly expressed his admiration for Zimbabwe's President Robert Mugabe, could prove to be an authoritarian president. But analysts said Mr Sata has muted many of his toughest stances in recent years.
In September 2013, Mr Sata dismissed growing opposition fears that he wants to turn Zambia into a one-party state.
Since taking office, his administration has frequently denied permits to opposition protests, and launched a raft of corruption cases against former officials now in opposition, including his predecessor, Rupiah Banda.