(CNN) Minnesota is the latest state to move toward making so-called "conversion therapy" illegal.

It's one of 39 states to introduce bills on conversion therapy, a widely discredited practice that seeks to change a person's sexual orientation or gender identity. Twenty-four states have introduced such bills just this year, according to The Trevor Project, a nonprofit organization named for the 1994 short film "Trevor" that works on suicide prevention among LGBTQ youth.

Lawmakers in the Minnesota's Democrat-controlled House voted last week on a measure that would ban mental health professionals from engaging in conversion therapy with anyone under the age of 18 or with vulnerable adults. The measure passed 72-53 as part of a larger bill about health and human services programs.

The bill has been introduced in the Senate but has not yet been voted on.

Here's a look at what conversion therapy entails and what states are doing about it.

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