Signed into law on April 19, 2004, Senate Bill (S.B.) 899, Stats. 2004, ch. 34 created the groundwor kfor Medical Provider Networks (MPNs) as an instrument to address concerns with upward spiraling medical costs and limitations on access to care. In 2013, major changes to the MPN system were implemented through passage of Senate Bill (S.B.) 863, Stats. 2012, ch. 363. This document discusses the statutory and regulatory provisions governing MPNs. For information on the other provisions of S.B. 899 and S.B. 863, see