In Washington, you have to be at least 18 years old to gamble in tribal casinos, while the minimum age to participate in charitable gambling is 18. However, the legal age to gamble in card rooms, poker rooms, and other licensed gambling establishments is 21. It is important to note that underage gambling is illegal and strictly enforced in Washington state. Make sure to verify the age requirements at specific gambling venues before participating. Always gamble responsibly and within the legal limits to avoid any penalties or consequences.