What is the legacy of the New Cross fire?
The victims, aged between 14 and 22, were killed in the blaze as they attended a 16th birthday party at 439 New Cross Road, Deptford, in 1981.
London Fire Brigade also held a guard of honour for the young victims.
Up to 300 people listened to a poetry reading and observed a two-minute silence as the plaque was unveiled.
On the night of the fire more than 100 guests had gathered at the flat for Yvonne Ruddock's birthday party. She was among those who died in the blaze.
In addition to the 13 youngsters who were killed in the fire Anthony Burbeck, who was at the party, died two years later.
Many people believe Antony took his own life as a result of what he saw that night and losing several of his friends and the plaque refers to 14 deaths, including his.
The original inquest, which began within months of the incident, returned open verdicts.
The investigation into the fire was reopened in 1997, following lobbying by members of the victims' families, and a second inquest was ordered in 2002.
That inquest also recorded an open verdict in 2004.
A memorial plaque has been unveiled in memory of 13 black youngsters who died in a fire at a flat in south-east London 30 years ago.