Leaders of the 84th Texas Legislature drafted and ratified HB 1164 (2015), prompting the Texas Education Agency to pilot a portfolio assessment option for assessing student writing growth and proficiency. The purpose of this study was to identify the perceptions, characterize the experiences, and identify the forces that influenced initial implementation of the statewide writing pilot. Through interviews with district leaders and the collection of open-ended questionnaires from participating educators, a collective case study method was conducted and allowed for analysis of cross-case themes. The identification of restraining and driving forces affecting implementation of the statewide pilot program provided insight into considerations for next steps in the evaluation of student writing achievement and growth. Three primary perceptions emerged as restraining forces influencing implementation: influences of inadequate funding, inconsistencies of implementation, and navigation of multiple assessment systems. Six primary themes related to driving forces influencing implementation were identified: using sociocultural and authentic methods, engaging in reflective practices, increasing volume and variety of writing opportunities, assessing student growth, aligning methods of instruction and assessment, and reducing stress for students. Effective professional development, dependent upon funding and staffing allocations; two-way channels of communication for participant reflection and feedback; and effective assessment structures must …