Clare Bailey is stepping aside as deputy leader of the Green Party in Northern Ireland after three years in the role.
She has said she wishes to give another person the opportunity to develop in the position.
Ms Bailey became deputy leader of the party in November 2014, working alongside party leader Steven Agnew.
In 2016, Ms Bailey became the party's second MLA after she was elected to represent South Belfast. She held her seat in the 2017 Assembly election.
She has been one of the main advocates for the party adopting a pro-choice stance on abortion, as well as the re-establishment of the party's LGBT group Queer Greens.
She will remain an MLA and party member.
In a statement, Ms Bailey said: "I have been given and gained so much as Green Party deputy leader across the past three years.
"The time is right for me to step aside and allow another person to develop the role of deputy leader.
"It's also right that another person gets the opportunity to develop themselves through the role.
"I am a busy South Belfast MLA and will put all of my efforts and energy into doing my very best for the people of the area."
Her replacement will be announced at the party's conference on September 30.