How do I turn down a job candidate after an extended interview process?

I would tell her a few specific things that particularly impressed you about her, to let her know that you are sincere and that this isn't just a form rejection letter that you are sending. Beyond that, if it's appropriate, you could tell her also that you were personally impressed with her qualifications and interview, and that you would have liked to bring her on board, but that in the end the organization as a whole decided to go with another impressive candidate. Then you could thank her for the time she put into the process. Above all, don't worry too much about this.Most job-seekers understand that the market is tight and that an interview doesn't guarantee a job. You don't need to feel too badly that you were unable to hire a good candidate.

Honestly - six weeks is nowhere near a drawn-out interview process. I work for the government and it is extremely common for our hiring to take more than a year. It is astounding, but true. Don't apologize. You have nothing to apologize for. You're great, she was great, the job was great, the applicant pool was great - someone just beat her out. Emphasize the position - she was a strong second and you liked her enough that you are still thinking of her. With this in mind, surely this candidate sees that you really liked and appreciated her. It will still sting that she was a close second for not one but two positions - but the fact that you invited her back to apply for another position is a real accolade. I would approach it from this vantage point, and emphasize what you really appreciated about her and think are particularly strong qualities. I'd encourage you to consider saying frankly that you really liked her and felt that she would be a great addition to COMPANY INATIZZY, and ask her if she'd like you to pass on her resume to other companies. This could potentially be the best professional accolade you can offer her, and a concrete realization that she is someone you are impressed by.

Maybe don't break the bad news until/unless the other candidate accepts?

Do you owe the candidate anything? No. Is more than two interviews unnecessary? Absolutely. It's an abuse of the job seekers time and will only brew disdain for your company. Absolutely, being upfront about them not receiving the position is the honorable thing to do. But, this practice of extended interviews is horrible.

Extreme discourtesy on the part of hiring organizations is so common these days that simply telling the candidate that they didn't get the job once you've decided makes you look like a class act, comparatively. Sad but true. I'd say something like this: "Unfortunately, the job is going to another candidate. Everyone was very impressed by you, but this is simply a situation where the other candidate came in with a background that was slightly stronger than yours and better suited to this position. While this didn't work out, we'd still love to find other ways to work with you down the line, and hope we can stay in touch and keep looking for the right opportunity."

I applied for a job and was told by people close to the hirers that I had it in the bag, went through the long process, and was ultimately passed over for another candidate. I got a phone call from one of the hiring committee, who said that she couldn't bear to just send me a form letter. It was a lovely phone call where she restated how impressed they were with me, told me how much support I had in the department, and shared - honestly - that it came down to years of experience. She also shared that she wanted to make sure we stayed in touch and that she looks forward to working with me in the future and would love to keep be posted on other developments and possibilities. It sucks to be invested and passed over, but I found the conversation heartening and it really reinforced my opinion and relationship with the organization.

I would make sure that when you call her up or email her, make sure that you tell her that she didn't get the position first. I went through a lengthy interview process last summer, and when they called me afterwards, they gushed about how much everyone liked me, only to say, "but we offered the position to someone else." It was a little upsetting because everything in his opening language for the first two minutes implied that they were calling to tell me I was getting an offer letter, and then BAM sucker punch! I'm fairly sure they were trying to soften the blow, but... I still appreciated the call and could tell that it wasn't just empty platitudes, though. So good on you for caring about her feelings in the process!

Amazon turned me down after 10 interviews, some of which were on site in Seattle, and I live on the opposite coast. As long as you are polite and professional you don't owe the candidate anything because they interviewed three times.

Besides telling her sincerely what you've said here (you think she's great, you'd love to work with her in some capacity in the future, etc.), offering to keep your ear to the ground and send her any openings in your field that look suited to her would be a really kind thing to do. Even if you never come across an opportunity to follow through with the offer, the feeling of having someone out there on your side is a nice thing to have when you're looking for a job (especially if she isn't currently employed).