The massification of national systems of higher education in recent decades and the rapid increase in the number of students have raised widening participation for students from underrepresented groups as a central policy agenda. In this study I focus on an overlooked group in the research literature -- student support practitioners, who provide advising and counseling services to students -- and explore how these practitioners negotiate and shape widening participation policies as part of their ongoing work. The study is based on interviews with 43 support practitioners working in 17 Israeli higher education institutions. It draws on the policy-as-practice approach and the theoretical construct of category work to explore how these practitioners interpret, adapt, and modify widening participation policies. The analysis reveals three practices of category work: creation, transformation, and disruption of policy categories: Practitioners create a new category of flexible and part-time studies, transform the category of students eligible for support by expanding its boundaries to include low socioeconomic status, and disrupt a target group's category by dissolving its boundaries, modifying its homogenous nature, and eliminating problematic support tools. This study contributes to our understanding of the gaps between WP policies and their appropriation, and of the processes in which local actors shape policy categories.