Approval
Look at the process by which hundreds of private schools have achieved accreditation in NEASC. The oldest of the six regional accrediting associations, the New England Association of Schools and Colleges was founded in 1885. It now claims some 1,848 schools and colleges in New England as accredited members. In addition it has over 92 overseas schools which have met its criteria. The Middle States Association of Colleges and Schools lists similar standards for its member institutions. These are serious, exhaustive evaluations of schools, their programs and their facilities.
Maintenance of Standards
Accreditation is not permanent. It must be maintained. A school has to demonstrate during a regular review process that it has developed and grown, not just maintained the status quo. The Obligations of Affiliation, for instance, of the North Central Association of Schools and Colleges specifically states that a member school must undergo review not later than five years after original accreditation was granted, and not later than ten years after each satisfactory review. As Selby Holmberg said in Education Week, "As an observer and evaluator of a number of independent school accrediting programs, I have learned that they are interested above all in standards of educational excellence."
Standards
I have used the word "standards" seven times so far in this short piece! But that's what accreditation is all about: standards, high standards, uniform standards. Please explore the regional accrediting association links more fully. They offer a wealth of information on this important subject.
Submit To Scrutiny
Think of accreditation as analogous to your or my gaining a doctorate. Attaining the first degree is fairly easy; the Master's is considerably more difficult; but a terminal degree requires the defense of your work and ideas before a body of your peers. You must undergo a careful scrutiny before you are found worthy. Then, once you have attained that lofty pinnacle, you must maintain your body of expertise or lose credibility!

