Hire a private teacher that is located in the Chicago area. This is something of an underutilized aspect of language learning. Often the first instinct is to start contacting schools when in many ways the school is a middleman. A language school has to not only pay the teacher to teach you, but they also have to pay for a lot of overhead costs. These costs (with a profit put on top) are passed on to you the student. Instead you might want to browse through local classified ads (or place one yourself) for a private teacher. This can drastically cut back on costs and gives you the added benefit of private instruction. It is important to keep in mind however what it is exactly you want to learn. Although your teacher can help you prepare for a certification test, this is not an option if you are looking for a certificate of proof of attendance in a course. In the Resource section there is a listing of Chicago-based classifieds that can help you begin your search.
Become a volunteer. There are various levels of mastery on the language acquisition scale, and perhaps your language is fluent in the sense you can make yourself understood but you lack the accuracy that you need to obtain a paid job or study. Try volunteering as a standalone approach or in addition to other more traditional methods of language learning. As a volunteer you not only practice and develop English, you also gain valuable work and life skills. You also get to work with people from the Chicago area and you can adapt yourself to their particular accents. In the Resource section there is a link to a Chicago group that organizes volunteering in and around the city. This will help you begin your search for Chicago organizations looking for volunteers.
Contact the immigrant center. If you are looking for an English course in the city of Chicago because you plan to, or are, immigrating, contact the local immigrant center to see if they offer free or reduced-fee classes. Immigrant centers offer a variety of classes aimed at both the learning of English as well as using English as the language of instruction to help you adapt to your new home. A link to the Illinois Coalition for Immigrant and Refugee Rights, which is based in Chicago, is in the Resource section.
Join a class in something you are interested in. Chicago is full of organizations that offer personal development courses. If you are a higher level learner, you may want to look into taking a course. A cooking course, a pottery course or dance lessons can be a great way to get exposure to the language. Taking a lesson in something that is of interest to you personally or professionally will give you vocabulary practice in an area that may not be otherwise covered in a more general English class. Remember that grammar will not change, but the vocabulary you need does.
Pay for classes at a private English school. There are a multitude of choices to fit your time frame and your budget. Decide if you want to take an intensive day course or a weekly night course. Consider if you want a home stay in addition to a class. The city of Chicago has a number of private schools that operate on the national as well as the local level. See the Resource section for where you can begin your search.