AIU and CTU are both regionally-accredited universities. Regional accreditation is the same accreditation as most major colleges and universities and is the highest level of accreditation available to an institution.

National accreditation, oddly enough, is a lower grade of accreditation that is used primarily for trade schools and technical colleges.

For clarity's sake: UCLA and Princeton are regionally accredited. ITT Tech and the California School of Culinary Arts are nationally accredited.

AIU has come under fire recently from SACS (their regional accrediting body) and was placed on probation. They have until 12/31/06 to come into compliance with their accreditor's demands. They are currently working with SACS to do so. CTU's accreditation is in no danger.

Both AIU and CTU are owned by Career Education Corporation. They are for-profit schools, so they naturally have a vested interest in attracting as many students as possible. It follows that people tend to be skeptical about the effectiveness of for-profit schools.

However, both are reputable institutions, and the degrees they issue are recognized by other major colleges and the US Department of Education as valid degrees.