What do I use as proof if I have lost my Citizenship Certificate?

What do I use as proof of my citizenship status if I have lost my Citizenship Certificate?

If you have lost your Citizenship Certificate, you can provide the US passport as a proof or evidence of Citizenship. You need to apply for a replacement of your Citizenship Certificate by filing Form N-565, Application for Replacement Naturalization/Citizenship Document.

Please make use of our quick and easy step-by-step system to prepare your Form N-565 online.

http://kb.immigrationdirect.com/Knowledgebase/What-do-I-use-as-proof-if-I-have-lost-my-Citizenship-Certificate