Across Europe, populist political movements have recently had considerable electoral success, in part based on portrayals of political elites as 'out of touch' with ordinary voters. These portrayals are often nourished by establishment politicians using overly complex rhetoric. Conversely, populist politicians often use simple rhetoric to signal commonality with voters. However, little is known about the causes and consequences of varying rhetorical complexity among elected officials. I argue that a plausible driver of variation in this dimension of political rhetoric is the nature and extent of political experience: as politicians amass legislative and governing experience, their language increasingly mimics the technical vocabulary of the legislative process. By implication, politicians' rhetoric becomes increasingly complex over over the course of a career. I test this implication in the context of the Danish parliament, from which I combine rich data on individual legislator careers with the complete record of legislative speech across three decades. Using a combination of established and novel measures of rhetorical complexity, I then characterize the trajectory of rhetorical complexity over the course of a legislative career. The results add to our understanding of the drivers of mass grievances fueling populist political movements.