July 22: Right-wing extremist Anders Behring Breivik sets off a bomb near the government building in Oslo, killing eight people and injuring dozens of others, before going on a more than hour-long shooting rampage on the nearby island of Utoeya, where the ruling Labour Party's youth wing is hosting a summer camp. He kills 69 people on the island, most of them teenagers, before he is arrested.
July 25: Breivik appears before a judge for the first time and is remanded in custody. Norway observes a minute of silence and between 150,000 and 200,000 people march in Oslo carrying roses, the symbol of the Labour Party, to commemorate the victims.
August 12: The government creates a commission tasked with determining what lessons to draw from the carnage. It is set to present its conclusions on August 13, 2012.
August 19 and 20: Survivors of the Utoeya massacre and loved ones of those who died there are for the first time permitted to visit the island.
August 21:Norway holds an emotional commemoration for the victims.
September 12: The populist anti-immigration Progress Party, of which Breivik had once been a member, suffers a severe setback in Norway's first elections - on the local level - since the massacre.
November 29: Two court-appointed psychiatric experts conclude that Breivik is psychotic, suffering from "paranoid schizophrenia", which means he should be locked up in a psychiatric institution rather than prison.
January 13: Amid continued controversy over the results of the first evaluation, the Oslo district court orders a new psychiatric examination of Breivik.
February: Breivik is placed under all but constant observation by psychiatric experts over a period of three weeks at the Ila prison, near Oslo.
March 7: Norwegian prosecutors formally charge Breivik with committing "acts of terror".
March 15: Norwegian police apologise for failing to arrest Breivik sooner.
April 10: The second team of court-appointed psychiatric experts say it has seen no signs that Breivik is psychotic and conclude he is criminally sane. But this assessment is not approved by the forensic psychiatric commission
April 16: Breivik's trial opens with him pleading not guilty.
April 26: About 40,000 Norwegians march in Oslo, carrying roses and singing a children's song hated by Breivik.
May 11: The brother of a young Iraqi Kurd killed on Utoeya throws a shoe at Breivik in court, but misses him.
June 21: The prosecution says Breivik's sanity has not been proven beyond a reasonable doubt and call for him to be locked up in a psychiatric ward instead of prison.
June 22: On the last day of his trial, Breivik insists his attacks were justified and demands his acquittal, while his lawyers argue he is sane and call for him to receive the "mildest possible" prison term.
July 22: Ceremonies are held to commemorate the first anniversary of the attacks.