MSPs are due to debate the general principles of a Bill which will make it easier for transgender people to be legally recognised as their preferred gender.
A stage one debate on the Gender Recognition Reform (Scotland) Bill is due to take place on Thursday afternoon.
The Bill aims to speed up the time it takes to obtain a gender recognition certificate (GRC), and also lowers the age for obtaining one from 18 to 16.
A group called Scottish Trans will hold an event outside the Scottish Parliament urging MSPs to support the Bill.
Earlier, a majority of MSPs on the Equalities, Human Rights and Civil Justice Committee supported the Bill, saying it brought in important reforms which would improve the lives of trans people.
However two Conservative MSPs on the committee opposed it.
They said they were “concerned that the removal of the requirement for gender dysphoria and the requirement for medical evidence may extend the GRC process to a large and more diverse group of people”.
This could open up the system to abuse by predatory men, they argued.
Concerns were also raised about the impact the reforms could have on single-sex spaces for women and girls – such as female-only toilets or changing rooms.
Earlier this month, opponents of reforming the Gender Recognition Act held a demonstration outside Holyrood.
Harry Potter author JK Rowling tweeted her support of the gathering, sharing a picture of herself wearing a T-shirt which branded Nicola Sturgeon a “destroyer of women’s rights”.
The First Minister said she disagreed with the author and described herself as a “passionate feminist”, adding that she respected people’s views on the matter.
Reform of the Gender Recognition Act was part of the co-operation agreement between the SNP and Scottish Greens which led to the smaller party entering the Scottish Government last year.
Speaking about the proposed changes, Social Justice Secretary Shona Robison said: “The Equalities, Human Rights and Civil Justice Committee have agreed with the principles of the Gender Recognition Reform Bill which is subject to debate in Parliament tomorrow.
“Legal gender recognition has been available for 18 years but many find the current system for obtaining a gender recognition certificate to be intrusive, medicalised and bureaucratic.
“The Bill aims to simplify and improve the process for a trans person to gain legal recognition, giving them better access to their existing rights.”
Ms Robison added: “Our support for trans rights does not conflict with our continued strong commitment to uphold the rights and protections that women and girls currently have under the 2010 Equality Act. This Bill makes no changes to that Act.”
However Scottish Conservative MSP Rachael Hamilton said she was “deeply concerned” about lowering the age for obtaining a gender recognition certificate, the reduction in the time someone has to live in their chosen gender, and the removal of the need for a medical diagnosis.
Ms Hamilton said: “It is clear that there are compelling and deeply held views on all sides of this debate, but the SNP Government risks doing more harm than good if they get this wrong.
“We must address the concerns that transgender individuals have with the current process, but this cannot come at the expense of putting at risk vulnerable people or protections for women and girls.”
The Conservative called on others to follow her party’s lead and give MSPs a free vote “so that we can scrutinise this legislation with the honesty and good faith it merits”.
