The Queen will preside over the summit, along with guests UN Secretary-General Ban Ki-Moon and French President Francois Hollande.
This year the CHOGM theme is 'adding global value', focussing on "making positive differences" in the lives of Commonwealth citizens and keeping the principles of liberty, dignity and prosperity at its centre.
But much like the unity rally held in Paris following the Charlie Hebdo attacks, where world leaders linked arms in defence of freedom of expression and the press despite their dubious records at home, there are serious doubts over some of the CHOGM leaders' commitment to the summit's ideals.
Indeed: the conference is only being held in Malta because the original 2015 host country, Mauritius, withdrew in protest against the alleged crimes against humanity committed by the Sri Lankan government during the country's long and bloody civil war.
The Queen will oversee proceedings at a banquet on Friday night in which she will shake hands with each leader in turn, including:
Sheikh Hasina, Bangladesh
Her government is accused of beating and imprisoning critics, journalists and activists
Hassanal Bolkiah, Brunei
The head of a tiny autocratic state which imposes Islam and punishes homosexuality with death
Paul Biya, Cameroon
The UN says the use of torture on citizens by Cameroonian security forces is 'widespread and systematic'
Narendra Modi, India
Accused of inciting racial hatred during 2002 riots that killed more than 1,200 people
Najib Razak, Malaysia
Malaysia can detain citizens indefinitely without charge and 'seditious' speech or writing is punishable under law
Muhammadu Buhari, Nigeria
Seized power in 1984-85 in a military coup; imprisoned 500 politicians, business leaders and journalists during a crackdown on corruption
Peter O'Neill, Papua New Guinea
Physical and sexual abuse of detainees - including children - by police and paramilitary police units continues to be widespread, says Human Rights Watch
Maithripala Sirisena, Sri Lanka
Failure to crack down on torture of detainees by police and abuses committed against ethnic and religious minorities, unwillingness to let international bodies investigate the recently-ended civil war
Barnabas Dlamini and Mswati III, Swaziland
Swaziland is plagued by severe discrimination against women, children, LGBT people, extrajudicial killings, torture and imprisonment by security services' restrictions on right to free assembly, political activity and freedom of the press
Yoweri Museveni, Uganda
Persistent persecution of the LGBT community, including the signing into law in 2009 a bill that makes homosexuality punishable by death
The only female prime minister present for the three day conference apart from Sheikh Hasina is Portia Simpson Miller, from Jamaica.
The Queen will also meet newly elected Canadian prime minister Justin Trudeau, New Zealand's John Key, and Australian Malcolm Turnbull, all of whom have won or re-won office in the last two months.