XSEDE starts providing the Open Science Grid (OSG) a dedicated IGTF-accredited CILogon CA instance providing the OSG community with digital certificates. OSG members can use CILogon, via the OSG PKI Certificate Request & Management System, to issue both end user and host/service certificates to secure their infrastructure. To date, over 500 OSG users have obtained end user certificates and OSG system administrators have obtained over 3,000 host/service certificates. The CILogon OSG CA instance leverages existing XSEDE CA infrastructure, including shared hardware security modules, to provide a cost-effective service to OSG.