English certifications: which ones are recognized overseas? In the European Union we have a "Common European Framework of Reference for Languages". In practice all language certification programmes have one of those levels associated to them (ranging from A1, the most basic, to C2, the most advanced), so that it is possible to establish equivalences between common tests. This allows me to, say, determine if my A in the (life-time valid) FCE exam is worth more or less than a 8.0 in the (short-lived) IELTS exam.

This however doesn't help the student that wants to have an exchange program outside the European Union. I heave heard rumours that, e.g., the Cambridge exams in English aren't accepted in the states, but that could very well be FUD.

What are the most universally accepted certifications in English?
From what I've heard, the TOEFL is well recognised. 

That being said, once you get your PhD, I don't think people ask for some English certifications (at least, I've never been asked to, and I'm not a native speaker). I guess your publications and the interview in English should be enough to see if you're able to communicate in English. 

EDIT List of who accepts the TOEFL.