My department has a number of courses we need covered by adjuncts in the next academic year. We were given permission to hire one (and only one) salaried adjunct and to cover the rest of the courses with per-course adjuncts. Salaried adjuncts receive benefits and are better paid than per-course adjuncts.

We received excellent candidates for the salaried position, only one of whom we can hire. After we close the search, (how) can I approach rejected candidates about teaching individual courses at the lower rate? Some career adjuncts have told me it would be offensive to offer a lower-paying and lower-status position to someone who applied for a better one, and I do not wish to offend anyone.

While the salaried position was publicly advertised, our institution does not advertise single courses. Furthermore, most of the candidates who applied for our salaried position were invited to by committee members or by our contacts, not because they were looking at ads.

How can I get the best outcome for our students and for teachers who would be willing to teach individual courses? I will continue to ask the administration for permission to hire a second salaried adjunct but do not expect to receive it. There is not much time to wait before starting our per-course search, as the current academic year is nearing its end (and our administration moves very slowly).

Don't ask them. It's a smack in the face. Advertise the position in the same place you advertised the salaried one; they will see it if they are still looking, and apply if they feel they need to.

Ask them. What other option do you have? Not asking them I guess, but then you're making the decision for them. Personally, I can't imagine being offended if you explain it the way you did above. That said, I do agree that most candidates will react the same way other answerers have ("no freaking way!") -- all the more so because they were personally recruited for a permanent, salaried position.

The only caveat I can think of is to have a firm offer for a specific course rather than just "inviting them to apply" for the lesser position. If possible, personalized mails or phone calls tend to be better received than form letters.

Yes, you should ask them. Here is how I would suggest doing it.

Give detailed and meaningful feedback on the unsuccessful application

Speaking as a PhD researcher who is approaching completion and who has applied (unsuccessfully) for various positions, the one thing that is most insulting is the lack of meaningful feedback. It is very demoralising to spend hours and hours preparing a job application, only to get a very terse and cryptic sentence or two of feedback loaded with clichés that give me no sense of how competitive (or uncompetitive) I am on the relevant facets of the position. Worst of all is the feedback that is largely or entirely positive, justifying the rejection only on some bizarre criticism or prejudice that gives me the impression that the interview was a complete waste of time (because the panel had already decided I was not "compatible"), even though I believed myself to be a serious candidate.

Get to the point quickly

Everyone is overloaded with correspondence, and a person reading a message about a job application may be nervous/excitable/apprehensive. So, please make the key information crystal clear at the beginning of the message (personally, I prefer to see it even in the subject line -- for example,

[unsuccessful, but we may have other opportunities for you] application for lecturer at Univ. of Academiapolis

-- some may find this too blunt, but it saves combing through the clichés of the message itself ("we had a lot of strong applications"; "we really enjoyed meeting you"), many of which can be found in both acceptances and rejections (I recently had a conference acceptance notice which looked like a rejection, because it started by talking about the very high standard of submissions and the difficulty in making selections, with the crucial point, "your paper is accepted", buried in the middle of the paragraph).

Ask permission to keep each applicant's curriculum vitae and application data on file

Depending on data-protection legislation, you may, strictly speaking, be obliged to delete the job-application records after having hired the chosen candidate, and may not be permitted to utilise them for other purposes. By asking permission to keep an unsuccessful applicant's data on file, you are treating him/her with respect, demonstrating implicitly an interest in hiring him/her for other opportunities, and giving him/her an opportunity to indicate whether he/she is interested. I would phrase it something like this:

Despite the negative outcome of this application, we were very impressed by you. We also have some hourly-paid positions for individual courses, and wondered whether that type of work might be of interest to you. If so, please confirm whether or not you give us permission to keep your curriculum vitae and application materials on file, with the view to possibly offering you some hourly-paid work without the need for a further interview (NB: we do not advertise these hourly-paid positions). Obviously, we appreciate that you may find the lower pay and fewer benefits of such hourly-paid work unacceptable, so if we do not hear from you, we shall assume you are not interested.

This sucks, but it is the reality of the academic job market. Basically, you want to offer them (hopefully), or ask them to apply (less nice, bordering on rude), the same job but now you are going to pay them less, likely substantially less, with fewer benefits and no long term security. Now, here is the hard part. If you don't offer them the worse job, they are going to walk away thinking they were not even good enough to adjunct on a per-course basis. I think that is worse than being up front.

You just need to be up front. Say "We cannot offer you the position you applied for." Then tell them you have a much less desirable position that they are clearly overqualified for, but if they are interested you would be happy for them to apply. If you actually want them to take the job, you also need to demonstrate that your department respects per-course adjuncts, despite the university clearly not respecting them. That is the hardest part. You cannot mislead them and pretend that there is a carrot (i.e., the job they applied for and the one you are trying to get them). It sounds like you care, but hopefully you have some evidence of why they should expect to be treated fairly.