<p>This seems unusual. If you have already been admitted, alumni may contact you to tell you about Caltech, but it's not an interview for obvious reasons.</p>
<p>What I would do is get in touch with the admissions office through the phone number on the main site, tell them what happened, and ask them what to do. You can also do this by email though it will take longer. You definitely should not ignore this or procrastinate, though, also for obvious reasons :)</p>
<p>Just be yourself.
My impression, they are very personal. If they see you are a 'fit' (of course your stats have to meet their standard first) then you will fit in their community. Otherwise if you are not fit, you weren't be happy there anyway.</p>
<p>thanks for all your responses. Yeah, it's very strange that it's the alumni himself contacting me for an interview while Caltech doesn't tell me anything. I think I should just contact Caltech about what I should do with this before I reply to this cool Caltech alumni. :)</p>
<p>I'd contact admissions, /unless/ you've already been accepted (then it's just outreach to prefrosh). But unless I'm seriously mistaken, we don't do interviews.</p>
<p>It turns out that Caltech does occasionally connect students with alumni to talk about Caltech before/during the application process. This is not an interview, just a way for the student to get some advice/background on Caltech if needed. But such an offer of help is purely optional and not connected to your chances in any way.</p>