The Center for Research Libraries (CRL) conducted a preservation audit of Portico between April and October 2009 and certifies Portico as a trustworthy digital repository.
Further information from the CRL and a link to the report itself can be found at http://www.crl.edu/archiving-preservation/digital-archives/certification-and-assessment-digital-repositories/portico.
Portico's announement of the certification can be found at http://www.portico.org/news/012510.html.
