Contact the university or college directly to find out if it is an accredited institution. This is the best way to determine if the university is accredited because there are some schools that set up their own accredited agencies to give the impression that they are accredited. Ask which agency or organization has accredited the institution and which programs are accredited. If the school has accredited itself, it's not truly an accredited institution.
Go to the USA Study Guide or the U.S. Department of Education Database of Accredited Postsecondary Institutions and Programs (see Resources) and look for the accreditation agency for your area or subject. Most states have accredited organizations for schools in general, but there are specific organizations set up to recognize industries; for example, the Accreditation Council for Pharmacy Education accredits pharmaceutical programs, the American Culinary Federation accredits culinary institutes that meet their standards, and the American Psychological Association accredits acceptable psychology programs offered at universities.
Contact the accrediting organization directly by locating the contact details found in USA Study Guide or by typing the name of the organization into a search engine. Most organizations will give you a list of institutions that have been accredited by them. It's the best way to ensure that the school you've chosen is accredited. Make sure you check to see which programs and courses of study have been approved.