The Mastery-Based Learning Collaborative (MBLC) is a demonstration project taking place in 47 schools in Washington State led by the Washington State Board of Education (SBE). The schools are receiving funding and participating in professional learning and a statewide network to support implementation of mastery-based learning (MBL) and culturally responsive-sustaining education (CRSE). The initiative's overarching goal is "to inform future policy by helping decision makers better understand what quality mastery-based learning looks like, how long it takes to implement, and what resources are necessary." This report presents evaluation activities and findings for the first year of Cohort 2, representing the planning stage of the MBLC initiative. The evaluation is intended to contribute to the identification of effective policies, practices, and system changes that can support MBL and CRSE implementation throughout Washington's K-12 education system. Data collection methods include a survey, interviews, and observations of cohort professional learning activities. The second cohort of schools believe strongly in the potential benefits of MBL and CRSE, with schools expressing high levels of motivation to continue improving their implementation. This positive outlook suggests a fertile ground for growth within these schools. In terms of developmental support, the SBE and Professional Learning Providers provided more than 14 hours of professional learning and 262 hours of personalized coaching to support schools' Year 2 work plan development. This report also explores a range of policy and non-policy factors influencing CRSE and MBL implementation, identifying a need for the SBE to play a more active role in navigating policy hurdles. By providing guidance and advocating for policy and structural changes that align with CRS MBL principles, the SBE can create a more supportive environment for schools pursuing these innovative learning models.