Originally elected in 2000 as a Republican member of the Texas House of Representatives for District 64, she retired after declining to seek re-election in 2016.
When Crownover's husband, a Denton veterinarian, died of leukemia after the 2000 primaries, his wife took his place on the general election ballot and ran unopposed.
"[6] In 2012, Crownover updated her campaign website to include the statement "we also were able to increase state funding for public schools by $1.6 billion even in the face of the worst recession in decades.
After the November 2006 general election, she stated: We have taken care of public school finance for right now, and I'm hoping this will be the higher education session.
[20] In 2009, she authored House Bill 2259 that required oil and gas drilling companies to clean up the surface of the land associated with inactive wells.
In 2011, Crownover coauthored House Bill 3328, which required natural gas drilling operators engaged in hydraulic fracturing to disclose the chemicals used in the fracking process; however, operators are only required to report the information to the immediate landowners, and the bill includes measures to protect industry trade secrets to avoid disclosure.
According to a news release from Crownover's office, since enactment of the legislation, more than 500 Texas newborns have been diagnosed and treated for disorders that, undetected, could have caused significant health problems or even death.
[24] Crownover also supported House Bill 15 during the 2011 session of the Texas Legislature, which requires a woman seeking to have an abortion in the state to first be subjected to a transvaginal ultrasound.