This chapter looks at the challenges that have faced – and continues to face – public affairs agencies in Brussels, and the ways in which agencies are responding to those challenges. It examines in particular the role that marketing plays in their responses, and how ‘thought leadership’ initiatives are changing the very idea of what a public affairs agency is, and what it does. A new niche developed for public affairs agencies that were able decipher the Parliament’s processes, devote resources to monitoring the activities of its committees, and develop relationships with its most influential members. Although the growth of ‘in-house’ lobbying operations in Brussels would appear to put the business of narrowly-defined public affairs agencies in question, many companies and interest groups – large and small – still use agencies. The chapter focuses on content-based marketing campaigns launched by Burson-Marsteller Brussels, one of the two biggest agencies in Brussels by revenue from lobbying activity.