Possessive of a college

[Toptomcat]

Hello.
I am a native English speaker, but I was unable to find any authoritative answer to my question anywhere else, and I hope that you folks can help me out.
I'm writing an application essay to a college named St. John's. What is the posessive of St. John's? In other words, is it "St. Johns’ educational approach", or "St. John's educational approach", or something more exotic?

[curmudgeon]

if it's good enough for them its good enough for me

The College

[Toptomcat]

Where on that page is it used in that sense?

[curmudgeon]

On the 'about' page:

Click here for an example of a St. John’s conversation

[MikeNewYork]

Originally Posted by Toptomcat

Where on that page is it used in that sense?

Here is one:

Despite the unquestioned zeal of St. John’s alumni for seminars, the next half hour offers irrefutable proof of the validity of Newton’s first law.

If one were to be very picky, one would write "St. John's's", but I doubt there is anyone who would actually do so.