"We have a thousand questions and we expect answers," said Georges Salines, head of one of several victims' associations represented Monday at the first of a series of hearings to be held over coming weeks.
Salines, a doctor, said he learned of his daughter's death at the Bataclan concert hall the day after the massacre there of 90 people at the hands of jihadist gunmen.
Recounting how he had heard of the death only indirectly through Twitter, he denounced an "atrocious lack of preparation" in terms of information-sharing on the bloody night itself and over the following days.
The commission of enquiry was set up at the request of the conservative opposition Republican party to look into the Socialist government's efforts to counter the terror threat since the Charlie Hebdo attacks the previous year.
"We are not prosecutors or judges but rather investigators (seeking) transparency... truth... and solutions," said commission president Georges Fenech.
Many told how they had learned of the death of a loved one only three days later, while others complained of saturated phone lines and employees' "shameful" behaviour at the main Paris morgue, which was overwhelmed.
Sophie Dias recalled that she was told when she came to identify her father at the morgue: "Don't worry, if you don't see the head you'll see a foot."
Still others questioned French intelligence services.
"How could a terrorist who was barred from France and Europe manage to direct an attack of such magnitude?" asked Mohamed Zenak, the treasurer of another victims' association.
He was referring to the suspected ringleader of the attacks, Abdelhamid Abaaoud, who was killed in a police raid on November 18.
The Belgian of Moroccan descent had been presumed to be in Syria when he was convicted and sentenced in absentia in July 2015 to 20 years in jail for helping to recruit foreign fighters for Syria.
Zenak, whose daughter was injured when a suicide bomber blew himself up at a bar in eastern Paris, pointed to security failures.
He said there had been no police presence at the Bataclan, nor were searches carried out ahead of a concert by US group Eagles of Death Metal.
A member of a third victims' association, Alexis Lebrun, claimed security services were aware of the potential of concert halls being targeted by jihadists.
The parliamentary commission will hold three hearings a week, and is expected to make its findings public on July 16.