Is it possible to give too much praise in a reference letter that supports a green card application?

Letters written for a green card application are very differently structured to letters written for other purposes. As was explained to me when I went through the process, the structure of a green card letter is usually

• I am awesome
• here are all the ways in which I am awesome
• because I am so awesome, you should trust me when I say that this person should get a green card
• and oh yeah, they're pretty awesome, which I can tell because I'm awesome.

I'm only slightly exaggerating here. The point is that GC letters are not read by academics - they are read by lawyers who don't evaluate technical skills so much as achievements and strength of recommender. So there's no way to go over the top really.

There a few signs that you might have gone over the top:

• Have you used many absolute superlatives ("the best" rather than "one of the best," "the most dedicated" instead of "extremely dedicated", and so on)?
• Is your letter too long or too detailed, given the length of time you have known the person (four pages is probably too long for someone who worked for you on a summer project, unless you've known that person independently in other contexts before then).

and most importantly

• Would such a letter, if you were the one receiving it rather than writing it, cause you to have an unfavorable or skeptical reaction about the candidate?

In other words, if it makes you think "nobody's that good," you've probably gone over the top.

Having been the recipient of a few recommendation letters when applying for a US Green Card, I can assure you it is impossible to give too much praise. The letters I received from my colleagues were humbling and, to put it mildly, embarrassing!!