Responding to calls for more substantive studies into ethical and responsible lobbying, we analyze data collected over a 5-year period in Brussels to explore how individual lobbyists understand the ethical dimensions of their work. Mobilizing insights from the sociology of the professions, we expose an emerging lobbying professionalism and unpack practitioners’ understandings of what being a professional lobbyist entails, focusing in particular on their espoused values of transparency and honesty. While expectations to lobby more transparently and honestly stem from political (...) institutions, we find individual lobbyists—acting as conduits—attempt to disseminate these expectations by setting limits that incite their clients to embrace what policymakers consider professional lobbying practice. Our study contributes to corporate political activity (CPA) scholarship by providing a professions-based understanding of ethical and responsible approaches to lobbying. We provide new insights into contextual and individual-level factors behind the emergence of such approaches, and elucidate implications of lobbying professionalism for business and European Union (EU) governance. (shrink)