If you do not renew your passport for 15 years, you cannot use renewal form DS-82 and need to use DS-11 (make a personal appearance). For DS-11, a US passport expired for any length of time is acceptable a proof of US citizenship.
Adults whose previous passport was issued when they were children need DS-11, this situation pertains to the poster.
This is all great information but too much of it is contradictory. And, sadly, too much comes from 2007-2010 which may mean it's outdated. I tried using the link provided way up top but it seems to be a dead link. When you go to the government page you get sent in six different directions with none being what you need. I even tried to find contact info on the gov page and, typical government stuff, none of it applied. How hard is it to provide a phone number and/or email address?
I need proof of citizenship for a program I'm applying to. However, the only proof of citizenship I have at the moment is the certificate itself; I haven't gotten a passport yet.
I'd really rather not have to use the original, but the front says something to the effect of "IT IS PUNISHABLE BY U.S. LAW TO COPY, PRINT, OR PHOTOGRAPH THIS CERTIFICATE, WITHOUT LAWFUL AUTHORITY." So, I guess I'm wondering if this really prohibits me from making a copy for a legitimate purpose?
Just want to update this old thread as it's coming up prominently when searching for this in Google - it looks like as of June 2021 Homeland Security has updated the warning mentioned above on newer naturalization certificates; 'ALTERATION OR MISUSE OF THIS DOCUMENT IS A FEDERAL OFFENSE AND PUNISHABLE BY LAW'