This report is the result of the largest public-private sector research project focused on open source software integrity, originally initiated between Coverity and the U.S. Department of Homeland Security in 2006. The results from the 2010 edition of the Coverity Scan Open Source Integrity Report detail the findings of analyzing more than 61 million lines of open source code from 291 popular and widely-used open source projects such as Android, Linux, Apache, Samba and PHP, among others.