Education leaders in hospice and palliative medicine (HPM) have long acknowledged the challenge of fellow performance assessment and the need for HPM-specific fellow assessment tools. In 2010, and in alignment with the Accreditation Council for Graduate Medical Education's (ACGME's) directive toward competency-based medical education, the national HPM Competencies Workgroup curated a set of assessment tools, the HPM Toolkit of Assessment Methods. The Toolkit has been a resource for HPM fellowship directors in evolving practical, multifaceted fellow assessment strategies. Now, as American Academy of Hospice and Palliative Medicine plans for a national workgroup in 2020 to define current HPM fellow assessment methods and to propose strategies to strengthen and standardize future assessment, the Toolkit provides a strong base from which to launch. However, the field learned important lessons from the 2010 Workgroup about the consensus process, gaps in areas of assessment, opportunities to address gaps with new or adapted tools, and limitations in implementing the Toolkit over time in terms of tracking, accessibility, and dissemination. This article describes the development of the Toolkit, including recommended tools and methods for assessment within each ACGME competency domain, and links the lessons learned to recommendations for the 2020 workgroup to consider in creating the next HPM assessment strategy and toolkit. Effective implementation will be crucial in supporting fellows to reach independent practice, which will further strengthen the field and workforce to provide the highest quality patient and family-centered care in serious illness. This will require an inspired, committed effort from the HPM community, which we enthusiastically anticipate.