The National Council of Teachers of Mathematics (NCTM 2014) takes a clear stance that each and every student should have rich experiences in mathematics classrooms. In 2015, the Every Student Succeeds Act noted that Universal Design for Learning (UDL) is an evidence-based, scientifically valid framework that fosters access to instruction for all children (Every Student Succeeds Act 2015). An important step in fostering rich mathematics for each and every student is implementing mathematics tasks with high cognitive demand and multiple entry points (i.e., low-floor and high-ceiling tasks). Such tasks give students the opportunity to problem solve and engage in reasoning and critical thinking. A comprehensive tool called the Thinking Through a Lesson Protocol (TTLP) that aims to help teachers make intentional choices about tasks and their implementation, and to encourage productive reflection that leads to action was created. In this article, the authors used the TTLP as part of year-long school-based professional development, and teachers found it helpful and rewarding. The authors describe a way that teachers leveraged a revised lesson planning guide to integrate UDL into their mathematics lessons. This revised lesson planning protocol helps teachers attend to the needs of diverse learners, aligns with UDL principles, and encourages use of rich mathematical tasks.