Many university-level electrical engineering courses continue to use textbooks as curriculum scaffolds, prescribed texts, and/or reference volumes. Textbook reliance is even more pronounced in courses that teach foundational principles of the discipline, such as introductory circuit theory. This paper reports on the conceptual coverage of introductory electric circuit theory as presented in textbooks. More specifically, a comparative study of six texts was performed using an analytic framework based on prior research on conceptual understanding and organized around multiple criteria. The ideas of conceptual framework and conceptual links are used to identify potential conceptual gaps in each textbook. This analysis reveals that the majority of the books are missing many important conceptual features. Findings from this study can be beneficial for authors as they develop new editions of books, and for instructors as they evaluate and select texts for use in their courses. This study can also inform ongoing efforts to both develop more effective instructional materials and investigate how textbooks affect conceptual understanding.