Costco's corporate policy is no firearms. It is not listed in the member's agreement. Alot of members on here, myself included, have been through this with Costco before. Employees there told me to just conceal. Out of sight, out of mind sort of thing. I no longer have a Costco membership. When it expired I went and got Sam's Club. If you don't already have a CPL you should get one. It helps when you go to places like this.