Spain's new king Felipe VI has taken over from his father Juan Carlos, who helped steer his country towards democracy after the death of the dictator General Franco.
Felipe received the royal sash from his father at the Zarzuela Palace near Madrid and has been proclaimed head of state in a ceremony in Parliament.
The 46-year-old acceded to the throne at the stroke of midnight after Juan Carlos formally abdicated on Wednesday.
The ceremony takes the form of a proclamation rather than a coronation. It is the first royal transition in Spain since democracy was restored in the 1970s, the BBC reports.
In a speech to parliament, Felipe thanked his parents and said he had "great hope" for the future of Spain.
"You will find in me a loyal head of state who is ready listen and understand, warn and advise as well as to defend the public interest at all times. The monarch wants to be close to citizens… ensuring it can preserve its prestige and dignity.
"Now more than ever, citizens of Spain are rightly demanding fundamental ethical principles should govern our public life. The king should not only be a reference but who serves all citizens of Spain."
The ceremonies have been relatively low key in keeping with an age of austerity, and questions are also being asked about a referendum on turning Spain into a republic.
Although Juan Carlos won plaudits for his role in restoring democracy, his image suffered when he went on a luxurious African elephant-hunting safari in the midst of a recession.
His reputation suffered further damage due to tax fraud allegations made against his daughter, Cristina, who is reported not to have been invited to the succession party.
No foreign leaders or royal families were invited to the event.