First of all, if your business already has insurance you can ask your agent to provide a Certificate of Insurance that simply is an evidence of what coverages and limits your business has, what company insures the business and the effective dates of the policy. If the event organizer wants to be named as an additional insured on your policy, be sure to let your agent know that, and verify if there is an additional premium for it.  You would also need to advise your agent of the scope of the special event, just to make sure it can be covered. If your business does not currently have liability insurance, or if for some reason your current carrier cannot offer coverage, there are numerous "Special Events" coverages out there designed for just this situation.  Your agent will be able to quote that for you.  Good luck with your special event!