Extensive changes have developed since the 1970s in the attributes and activities of labor unions and business organizations as political interest groups (e.g., Mizruchi, 2013; Rosenfeld, 2014). To facilitate assessment of the scope and content of the explanation devoted to these interests in American government textbooks, these developments were reviewed and summarized and an inventory of topical coverage was developed. An initial topical list was developed on the basis of experience and a priori assumptions and iteratively expanded via review of chapters and subsections on interest groups and their activities in an opportunistic sample of twelve textbooks. Explanations of specific topics and links to business and labor interests for each subtopic were tabulated, including assessment of direct or indirect reference and limited or detailed explanation, with expectations adjusted for the context of an introductory textbook. The reviews and tabulations demonstrated that while textbooks may idiosyncratically introduce various of the more than 170 potential topics identified, attention was concentrated on a few indicators of strengths and weaknesses, a few methods of political process participation, and a limited selection of high profile laws, regulations, and court cases. Process, policy, and systemic impacts were infrequently identified or explained. Explanation of labor unions tended to be brief and superficial. Explanation of the political activities of business interests was relatively more extensive and detailed, although often based on allusion and examples, and explanation of the different types of business organizations and interests was generally truncated, and holistic views of business influence were generally eschewed. Developments since the 1970s were generally ignored. Treatment of interest group theory continues to be extensively focused on the concept of pluralism, but also tends to recognize unbalanced participation and influence as an empirical reality. Salient topics for further analysis of interest group politics are discussed.