About 50 million voters are heading to the polls in Thailand for the first general election since the 2014 coup.
Thailand has been buffeted by political instability for years, largely a battle between supporters of the military and ousted former PM Thaksin Shinawatra.
After seizing power the army promised to restore order and democracy, but has repeatedly postponed the vote.
Critics say a new constitution the army introduced will ensure it remains influential whatever the outcome.
Turnout is expected to be high for this first election since 2011.
More than seven million people aged between 18-26 are eligible to vote for the first time and could be key to victory, so all parties have been keen to court their vote.
On the eve of the election, Thailand's King Maha Vajiralongkorn issued a statement urging "peace and order" during the voting process.
The statement, which was featured on national television on Saturday evening, urged voters to "support the good people".
The election is primarily a contest between pro-military parties and allies of Mr Thaksin.
He was ousted in a coup in 2006 and lives in self-imposed exile to avoid a conviction for abuse of power. But he still has a significant following, largely among rural and less affluent voters.