Kansas law requires charitable organizations to register with the Secretary of State's office prior to soliciting. The law also requires professional fundraisers and solicitors working for a charitable organization to register - something to keep in mind if you receive a telemarketing call from a for-profit fundraiser on behalf of a charitable organization.
Being a law, it is filled with exemptions. You can view those here. Of note are religious organizations, Boys and Girls Clubs, scouts, and any charity that receives funds from the United Way.
For more information about charity registration requirements in Kansas, visit the website of the Kansas Secretary of State.