Legal Question in Landlord & Tenant Law in Illinois

Well there are a number of things. First, make sure you complied with whatever leasing rules there are. Next, check your condo bylaws and rules. There may be a rule requiring you to "deaden" sounds through floors, through carpets, rugs, underlayment.... If so that may be your responsibility to impose on your tenant (most condo leases require the tenant to comply with condo bylaws and rules) but it is up to you as owner to enforce. There may also be (as in most situations) a nuisance bylaw/rule about noise, and there may be one in the lease. If you receive a complaint, as landlord you need to identify exactly what the nature and extent of the complaint is -- people can't just say there's too much noise and that's it. But once you ascertain your obligations as a neighboring owner you should probably have a talk with your tenants and take a look see as to what may be the cause -- be careful under the Chicago Residential Landlord & Tenant Ordinance you must give prior notice for such a visit. If they are cooperative it may just end there. If not or it continues anyhow and you get further complaints, you may have to visit the people downstairs a couple of evenings to see what they're talking about, or until you hear what they hear -- you should do it as a friendly thing. If you concur that the noise is excessive, and if your lease provides for noise to be a tenant default, you will have the right to give you tenant a landlord's notice -- the type may be specified in the lease or if not then by law -- it may be a 10 or 30 days' notice; you'll have to see which one applies to your situation. Note that could lead to your terminating their lease! But be careful too to be involved, the owners downstairs could report the situation to the condo association and its management company and things can escalate from there. Grab the bull by the horns; be firm but fair! PS I think there are a couple of places in the law where 9 pm is a standard for some kinds of things (telemarketing for example) and so 9:30 may just be unreasonable, or it may have become such an irritant to the neighbors you may not be able to negotiate anything. There are children involved and kids do make noise without thinking about it; in a multifamily situation it's always a balancing act. Good luck.