From the BBC, writer Mark Doyle unpacks the report for us.
The report says more than a third of people made homeless by the massive earthquake in January 2010, and now living in tents, still do not have access to clean water, and a quarter still do not have a toilet.
This is despite highly-publicised promises of help by aid agencies and foreign governments.
The report, by New York's City University, is based on a survey by Haitian sociologists. It says aid agencies have failed to address the real causes of the cholera outbreak - including widespread poverty and unemployment that was endemic before last January's earthquake.
"Much more progress needs to be made", says the enquiry; "not only in aid delivery but in coordination".
The new study says the international community and the Haitian government failed to capitalise on the movement of people out of the capital Port au Prince in the immediate aftermath of the quake.
Aid agencies and the Haitian government should have worked outside Port au Prince, the report says, and "seized the moment to initiate job creation to rebuild rural Haiti's delapidated infrastructure".
"Instead, all the food-for-work and cash-for-work, not to mention aid distribution, was centred in Port au Prince. Predictably… the camps swelled to an estimated 1.7 million people at their peak, making the aid response more difficult".