The Fashion Transparency Index also looks at the information supplied on their environmental impact...
Clothing brands are being accused of not revealing enough information on workers' rights and their environmental impact.
The Fashion Transparency Index says customers need to know whether their money is supporting human rights abuses or environmental destruction.
The release of the new report marks four years since a factory collapse killed more than 1,000 clothing workers in Bangladesh.
It ranks 100 of the world's biggest fashion and apparel brands and retailers according to how much information they disclose about their suppliers, supply chain policies and practices, and social and environmental impact.
The 2017 index gave Adidas and Reebok the highest score of 121.5 out of 250, whilst Marks & Spencer and H&M also ranked highly.
Only eight scored higher than 40%. Some 32 brands scored 10% or less, revealing a limited number of policies and procedures.
Nine brands scored 4% or less – Dior, China's Heilan Home and Germany's s.Oliver scored zero for disclosing nothing.
The average score for all brands is just 49 out of 250, roughly 20% of all possible points.
One of the big takeaways is that there's still "a long way to go" towards the fashion industry paying a living wage.
Although 34 of the 100 brands have made public commitments to paying living wages to workers in the supply chain, just four – H&M, Marks & Spencer, New Look and Puma – are reporting on their progress towards achieving this aim.
Other key findings from this year's index include:
The index is compiled from public domain information by Fashion Revolution, the biggest global movement campaigning for a fairer, safer, cleaner industry.
Carry Somers, founder and global operations director of Fashion Revolution, said of this year's findings:
"The journeys made by our clothes remain largely unseen. They may have started life in a field and then travelled
across a vast network, in many countries, through the hands of hundreds of workers, working for dozens of different companies, before reaching our wardrobes."
Orsola De Castro, Fashion Revolution founder and creative director, added:
"Transparency encourages scrutiny, vigilance and accountability.
"It's like opening one's front door and allowing others to look inside; not yet the full picture, but an important step towards openness and public disclosure. And, of course, the more doors are open, the more the picture becomes clearer, the better we can understand and ameliorate supply chain workers' lives and the environment."
In January, Channel 4's Dispatches exposed working conditions in factories supplying some of Britain's leading fashion chains.
It documented factory bosses paying workers as little as £3 per hour to make clothes for River Island, Boohoo, Missguided and New Look at factories located in the UK.
Hidden cameras recorded bosses refusing to agree a payment rate with the reporter before beginning to work in their factories.
Irish headlines were also made in 2015, when a letter claiming to be an SOS message from a Chinese prisoner was found in a packet of socks bought in Penneys store on Dublin's Mary Street.
The note was discovered by a shopper living in the capital, who found it hidden in the bottom of a sock and sent the document to Newstalk.