The use of smartphones for mobile banking and payments at the point of sale (POS) or remotely (e.g., mobile app, in-app, browser) continues to grow. A 2017 Forrester study predicts that the volume of mobile payments will triple by 2021, growing at a 20 percent annual compound rate. In spite of this predicted growth trend, the market remains highly fragmented, with many different solutions available to consumers and financial institutions (FIs). No open industry standards have emerged to guide this development, which would greatly benefit the ecosystem. For this reason, the Accredited Standards Committee (ASC) X9 has undertaken the X9.134 initiative to develop a domestic mobile financial services (MFS) standard modeled after the ISO 12812: Core Banking – Mobile Financial Services standard and technical specifications published in 2017. This brief describes the purpose and scope of the X9.134 standard work effort and future expectations for U.S. industry adoption of a mobile banking and payments standard.