The Astrophysics Source Code Library (ASCL) is a free online registry for source codes used in astronomical research, established in 1999. Housed on the Astronomy Picture of the Day (APOD) forum, the ASCL has grown to include over 500 codes as of October 31, 2012, making it the largest resource for astrophysics software. The ASCL actively seeks out new and old codes used in refereed journals and is indexed by the SAO/NASA Astrophysics Data System (ADS), making the codes citable and discoverable. The ASCL has seen significant growth, with an average of 18 new codes added monthly since its move to a new site in mid-2010. The library is supported by an Advisory Committee and is demonstrated at conferences, such as ADASS, where it is used to cite and link software in publications and pre-prints. The ASCL's activity is measured using Google Analytics, showing a steady increase in page views over time.The Astrophysics Source Code Library (ASCL) is a free online registry for source codes used in astronomical research, established in 1999. Housed on the Astronomy Picture of the Day (APOD) forum, the ASCL has grown to include over 500 codes as of October 31, 2012, making it the largest resource for astrophysics software. The ASCL actively seeks out new and old codes used in refereed journals and is indexed by the SAO/NASA Astrophysics Data System (ADS), making the codes citable and discoverable. The ASCL has seen significant growth, with an average of 18 new codes added monthly since its move to a new site in mid-2010. The library is supported by an Advisory Committee and is demonstrated at conferences, such as ADASS, where it is used to cite and link software in publications and pre-prints. The ASCL's activity is measured using Google Analytics, showing a steady increase in page views over time.