The exact structure of a reference letter will differ slightly depending on the type of reference it is, but this is a good basic outline:

1. Start using the business letter format: put the recipient’s name and address, if known, and address them as “Dear [name]”. If the recipient is currently unknown (this would be likely on an academic application, for instance), then use “Dear Sir/Madam” or “To whom it may concern”.
2. It is often helpful to introduce yourself in the first couple of lines of your letter. The recipient will not need your life history: just give a brief sentence or two explaining your position and your relationship to the candidate.
3. Your next paragraph should confirm any facts which you know the candidate will be supplying along with your letter. For example, if you are writing a reference for a job applicant, some or all of these details may be appropriate:
   • The person’s job title, and role within the company.
   • The person’s leaving salary when they were last employed by you (or your organisation).
   • The dates which the person was employed from and until.

   If you are writing a reference letter for an academic course, you will need to confirm the person’s academic grades.

4. In your third paragraph, you should provide your judgement upon the candidate’s skills and qualities. It is often appropriate to state that you would gladly re-employ them, or that their contributions to your college class were highly valued. Single out any exceptional qualities that the candidate has – perhaps their drive and enthusiasm, their attention to detail, or their ability to lead.
5. Where possible, use your fourth paragraph to give a couple of concrete examples of times when the candidate excelled. (You may want to ask the candidate to tell you about any extra-curricular projects they’ve been involved in, or invite them to highlight anything they’d particularly like you to include in the reference letter.)
6. Close your letter on a positive note, and if you are willing to receive further correspondence about the candidate’s application, make this clear. Include your contact details too.
7. As with any business letter, you should end appropriately; “Yours sincerely” when you are writing to a named recipient, and “Yours faithfully” when you do not know who will be receiving the letter.