A team led by Gillian Abel from University of Otago, Christchurch, interviewed 772 sex workers for the book Taking the crime out of sex work - New Zealand sex workers' fight for decriminalisation.
Abel says they found decriminalisation of New Zealand's sex industry has resulted in safer, healthier sex workers.
"The book provides compelling evidence decriminalisation has achieved the aim of addressing sex workers' human rights and has had a positive effect on their health and safety."
It found sex workers have knowledge of their employment rights and are more likely to assert them. They also have a better relationship with police and are more likely to report violence, but there is still stigma associated with the job.
An area of concern that emerged was transgender youth, who the researchers found are particularly vulnerable to being drawn into the industry and need greater support.
Abel says transgender workers tend to work either privately or on the street. She says street-based workers are still acknowledged as being the most vulnerable sector of the sex industry - even in a decriminalised environment.
"Transgender participants in our study tended to start sex work, on the street, at an early age because they had often left home as a result of conflict within their families about their gender identity," she says.
"They then found some sense of community with other transgender people on the street."
Abel adds that when transgender participants tried employment in other occupations, they were often discriminated against and made to feel like everybody was staring and talking about them.
Abel says there needs to be more support for transgender youth, while Government social policies need to be improved overall to protect all those aged under 18 entering sex work. She cites freeing up access to the independent youth benefit as one possible way forward.