Austin ISD will require masks for all students, staff and visitors when the new school year begins next week.
The rule, announced at a Board of Trustees meeting Monday night, goes against Gov. Greg Abbott's executive order banning mask mandates at Texas schools. It follows Dallas ISD's announcement that it will also require masks at its schools.
In Houston, HISD Superintendent Millard House II has said he also wants to issue a mandate in the state's biggest district. The school board will meet to discuss the idea this week.
Meanwhile, the nonprofit Southern Center for Child Advocacy has filed a lawsuit against Abbott and his executive order. The group seeks to give local school districts the power to enforce mask wearing.
In addition, Dallas County Judge Clay Jenkins has filed a lawsuit against Abbott over the power to enact bans on mask mandates.
Similar fights are playing out in other states as districts in Arizona and Florida have defied orders prohibiting school mask mandates.
In Arkansas last week, a judge temporarily blocked a state ban on mask mandates, and Republican Gov. Asa Hutchinson admitted signing the ban into law was an "error."