Business groups may represent one corporation, a trade association, or a broad business federation. They lobby over regulation, taxation, trade, and procurement and often possess specialized information and sustained resources. Labor unions represent workers in collective bargaining and public policy, advocating wages, benefits, safety, and labor law. Their organizational base and policy positions differ from employers', though the two can support the same infrastructure or training program.

Professional associations represent occupations such as physicians, teachers, or lawyers. They may provide credentials, continuing education, standards, and member services while lobbying on regulation and working conditions. Their expertise helps officials evaluate technical policy, but self-interest can shape the information they present. Policymakers should distinguish useful knowledge from legal authority: an association can recommend a rule but cannot enact it.

Concentrated economic interests often organize more easily because each participant has a visible stake. That advantage does not guarantee victory, and noneconomic causes can build large memberships through moral commitment, networks, and effective leadership. Classify a group by whom it represents and the policy benefit sought; do not infer that every economic group is a business group or that every public cause lacks material consequences.

Video lesson: Interest Groups: Crash Course Government and Politics #42