Funnily enough, I've slowly been working on a post on what it is like to write letters of recommendation for people at different stages of their careers, as part of a series of posts I'm hoping to write on aspects of being a Professor. Then along comes Julianne's (rather innocuous and humorous in my opinion) post, and all kinds of craziness breaks out in the comments. So I'm still working on the other post, but I thought it might be useful to provide some unvarnished facts about letters that I've picked up over the years. Most certainly everything that I'm about to write is anecdotal, based on my own direct experiences, and acquired through conversations with colleagues. Nevertheless, I have carefully read literally many thousands of letters of recommendation for graduate students, and still more thousands for postdoctoral and faculty positions combined. So feel free to weigh that any way you see fit. So, some observations: 1. I have never, ever, seen, nor heard of, a straight out negative letter for a graduate student. This applies to letters coming from the rest of the world just as it applies to US letter writers. 2. It is true that letters from European letter writers tend to be more reserved than those from their US counterparts. However, this doesn't make them any more useful, since what matters is calibration. If a given letter writer is equally reserved when writing about a mediocre candidate as they are when writing about a tremendous one, then that's just as much a problem as effusive letters for them both. 3. Speaking of calibration of letters, one way committees can establish that is through consistency between the strength of the letter and the student's grades. Just to be clear, it is, of course, possible that a letter writer believes that a student will be very successful despite unremarkable grades. But if this is the case, then the writer needs to explain why in the letter, so that the committee can make an informed decision about how to rank the file. By the way, it is also perfectly possible that a person with poor grades and who hasn't convinced letter writers of their excellence in some other way, nevertheless secretly has the potential to do wonderfully in graduate school and in research. Nobody denies this, but an admissions committee faced with a file like that has very little choice but to deny entry. How would they know to do otherwise? One can't expect the committee members to be mind readers. 4. When writing for a graduate student, it is quite possible to write a letter that only emphasizes their positive aspects, but still won't help that much to get them in. In part, this is because one is usually asked to numerically compare a graduate applicant with their peers: something along the lines of "How do you compare this student's potential for success in research with others at the same level you have encountered? Top 5%, 10%, 20%, ...?" There are usually other questions, replacing "research" with other qualities. No matter how much one likes a student, one is most certainly supposed to be honest here. 5. Rather frequently, one reads something in the personal statement that makes the reader wince. It may be immature, it may be a little unprofessional, it may be a little arrogant, or it may show that the student is entirely unfamiliar with the program that he or she is applying to. The last example may rightly sway the committee somewhat, although the truth is that if the candidate is very good, they'll overlook it immediately. The others are extremely unlikely to have any effect on the candidate's chances of admission, although the committee may giggle over them a little (the members are, in fact, human). 6. Most letter writers are writing for more than one person in a given year, or to the same institutions in multiple years. If one's letters are to be trusted, it is crucial for readers to be able to - you guessed it - calibrate one's letters. This means that even if you are writing letters that truly recommend each candidate, if you feel that there is an honest to goodness hierarchy among the people you're writing for, then you owe it to both the candidates and the institutions to express that, although how strongly one chooses to do this will vary. I do not think that these are controversial statements, nor do I think many Professors will quibble with them too much, even though some may have seen a few negative letters, or perhaps find one type of letter a little more useful than another. Perhaps the most important thing for prospective graduate students in particular to keep in mind is that admissions committees, while certainly holding great power over individuals' futures, are in fact desperately seeking good candidates, and are willing to overlook all kinds of blemishes, indiscretions, and specific weaknesses if they feel that they're getting a fundamentally good candidate. A single specific fact about an application is very unlikely to ruin a person's chances (you'd be amazed at the GRE scores of some students admitted to even the top programs). Rather, the committee tries to get an overall picture of the candidate, and then to rank them relative to other candidates (also taking into account the department's research needs at a given time). Only then are admissions decision taken. I have certainly missed some issues and subtleties here. But the basic idea should be clear and, if my own experience is anything like typical, then it should help some of you, particularly prospective graduate students, to understand what really goes on with letters. It is quite terrifying to ask people for letters and not to know precisely what's said in them. Hopefully it helps to know that mostly, by far, you can rely on people to do what they can for you, without being dishonest (and this is important - you can't expect them to write that you're one of the best students they've ever seen if they don't think that is the case). For the record I personally don't write negative letters for people. For those that I can recommend at some level, I tell them what kind of letter (generally, no specifics, of course) they can expect from me for the kinds of positions they're applying for. They can then decide whether they still want me to write.