How to write a letter of recommendation
Brian Junker

GENERAL COMMENTS ON WRITING LETTERS OF RECOMMENDATION

With very few exceptions all letters of recommendation have a
generally positive tone about the candidate.  Within such a letter you
can still communicate whether you are in fact positive, neutral or
negative about the candidate's application, according to the amount
and kind of evidence you provide, and the story you tell, about the
candidate (my "neutral" letters contain the least specific evidence).

I usually open my letters with a summarizing statement, like "I am
writing to __________ that JOHN DOE be admitted to ________ ."  The
first blank is something like "enthusiastically recommend" or "give my
recommendation", etc., and the second blank is the position.  After a
while you develop a personal calibration for phrases like "hope you
consider", "strongly recommend", "enthusiastically recommend", etc.  I
usually close the letter with a 1 to 3 sentence parag summarizing the
candidate and repeating my recommendation from the first sentence.

Between the opening and the closing you typically tell how (and how
long) you know the candidate, relevant evidence that you are uniquely
able to provide, etc.  [You should not repeat information in the
candidate's vita, although you may be able to provide "background"
that helps the reader to interpret the vita or other evidence in the
application materials.]

Length is a big deal.  If the letter is too short it suggests you
don't know or don't care enough about the person to write a full
letter; if it is too long it suggests you are "reaching" for praise
that may not be warranted.  In addition, very long letters will not be
read carefully.

My typical letter for an undergrad is a page or less of text for the
body, plus address, salutation, closing, etc.  The whole thing often
fits on one page.

My typical letter for a grad student applying for an internship or
scholarship is a page and a half or so.

My typical letter for a job applicant is two-ish pages.

My typical letter for a faculty reappointment or promotion case runs
about three pages or so.

The differences that contribute to the length are

   (a) whether there is a story to tell about my relationship or
       interactions with the candidate.

   (b) the kind and length of anecdotal evidence (for an undergrad, a
       short anecdote about classroom performance or a project is
       usually all I have; for a promotion letter I may take three or
       four papers and write a paragraph on each, in addition to
       paragraphs on teaching, personal attributes, career trajectory,
       mentoring, etc.)

I am probably a bit more wordy than many letter writers.

Even in longer letters it is important to put the meat of the matter
in the first paragraph, and to summarize the highlights in the last
paragraph.  Letters are read twice: first superficially to screen for
"top candidates"; and then, for those who pass the screen, the letter
is read a second time carefully to make hard choices about who to
select.

There are exceptions to all of the above rules.  For example if the
reader of the letter knows you (the writer) well, a one-sentence
letter can carry more positive weight than three or four carefully
worded paragraphs!

GENERIC OUTLINE FOR A LETTER OF RECOMMENDATION:

This outline is based on the idea that your letter will be read twice:

First time: only the first and last parag of your letter will be read, to
  quickly decide whether the candidate goes in the "reject" pile or goes 
  in the "possibly consider" pile.  [It is not unusual to have to read three
  letters each for 150 applicants for a job or grad school appointment, for
  example.]

Second time: If the candidate is in the "possibly consider" pile, the body of
  your letter (everything between the first and last paragraph) will be read
  more carefully, to try to distinguish your candidate from other candidates,
  in order to make a final selection decision.

Here is the generic outline. Nowadays almost all my letters follow this
outline: 

Opening paragraph:

  "I am writing to [highly recommend] JOHN H. DOE for
  [position/honor/etc] at [place].  Mr. Doe is a [one-sentence
  description highlighting John's relevant features]."

Historical paragraph: 

  [short historical parag - how I got to know john and/or how he came
  to my attention. This is a good place to state or imply your
  qualifications as well (don't dwell on yourself though; you will
  give the impression you don't have enough to say about the candidate
  and are filling space). Sometimes this is just the first sentence of
  the more meaty paragraph to follow.]

Meaty paragraph(s):

  What is john into, one or two intellectual or substantial anecdotes
  that reveal john's relevant strengths...

Personal paragraph: 

  What is john like as a person and how does this interact with his
  relevant professional qualities.  *Maybe* also personal anecdote(s)
  if highly informative or relevant.

Closing paragraph:

  First sentence: "JOHN DOE is a [one sentence sharply focusing on
  most salient features of john for this position/honor/etc]."  Then
  an optional sentence elaborating on features and/or suggesting the
  benefits john will get from the honor and/or benefits john will give
  to the organization that honors him.  Final sentence (not optional!)
  reprises recommendation from first parag: "deserves a chance",
  "highly recommend", "recommend without reservation", "you will not
  be disappointed", "a real star", etc.

Contact Info:

  "Please feel free to contact me using the information in the letterhead
  if you have any questions or need additional information."

LENGTH:

If some of the above can be omitted or compressed (and in many cases
it can) it is reasonable to keep the letter to ONE PAGE total.

If all of the above is included, try very hard to keep the letter to
TWO PAGES total.

Letters of MORE THAN TWO PAGES are generally viewed as "guilding the
lilly" or "trying to think of enough small nice things to say to cover
up some larger weakness".

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