Recent curricular interventions in engineering education have focused on encouraging students to develop an entrepreneurial mindset (EM) to equip them with the skills needed to generate innovative ideas and address complex global problems upon entering the workforce. Methods to evaluate these interventions have been inconsistent due to the lack of agreement on a definition of EM. Concept mapping has demonstrated its efficacy as an assessment method for complex constructs in engineering disciplines, particularly when employing the categorical scoring method; however, further research is required to enhance its validity evidence and usefulness in assessing EM. This paper presents a categorical codebook for EM concept maps to be applied when assessing engineering students. Our finalized codebook consists of six main categories and sub-tags that provide additional context for each main category. We expect that this codebook and our refined scoring process will be beneficial for future EM assessment.