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The short answer to your question is likely what you looked at first, "What does Your Lease Say?"  If you have no relief there, is there anything in writing that they gave you promising that you would have that right? The problem with a written document like a lease is that it is the contract, the full agreement.  There is likely a paragraph that says just that, something like, "this lease contains all agreements between the parties concerning the rental of the premises.  All other discussions are hereby superseded.  The next possibility is, "who told you that you had that right?"  Have you spoken directly with them?  Can you guilt them in to acknowledging the truth?  Are there any other temporary signs?  Talk to the other tenants, were THEY allowed to put up temporary signs (actually, it may be your neighbors who don't want you to have a temporary sign). One possibility if you can get no relief otherwise is, "is the landlord willing to pay for your new signage and then amortize the cost of the sign over the remainder of your lease?  That could be the best of both worlds for you, even if you had to pay a small premium for the use of their money during the term of the lease.