This paper describes the rationale for, and the design, implementation and preliminary evaluation of a taxonomy to guide the grading and feedback of ePortfolio assessment of personal development planning (PDP) in a module where PDP is integrated into the curriculum. Conventional higher education assessment methods do not adequately address the requirements of this innovative approach to learning and assessment, and a new assessment tool was felt to be necessary. Drawing on recent theories in the fields of constructive alignment, reflective practice and assessment for learning, a criteria-based taxonomy was designed with the aims of articulating criteria for achievement aligned with the learning outcomes of the module, and of ensuring valid and reliable evaluation of student achievement. Analysis of student and tutor feedback and statistical comparison of marks achieved after the pilot study have produced encouraging results. While this taxonomy was designed to be used in specific circumstances, it is capable of being adapted for use by others who deliver modules or courses where PDP embedded in the curriculum is supported and assessed by means of an ePortfolio.