Although political methodologists are well aware of measurement issues and the problems that can be created, such concerns are not always front and center when we are doing substantive research. Here, we show how choices in measuring legislative preferences have influenced our understanding of what determines legislative outputs. Specifically, we replicate and extend Binder's highly influential analysis (Binder, Sarah A. 1999. The dynamics of legislative gridlock, 1947–96. American Political Science Review 93:519–33; see also Binder, Sarah A. 2003. Stalemate: Causes and consequences of legislative gridlock. Washington, DC: Brookings Institution) of legislative gridlock, which emphasizes how partisan, electoral, and institutional characteristics generate major legislative initiatives. Binder purports to show that examining the proportion, rather than the absolute number, of key policy proposals passed leads to the inference that these features, rather than divided government, are crucial for explaining gridlock. However, we demonstrate that this finding is undermined by flaws in preference measurement. Binder's results are a function of using W-NOMINATE scores never designed for comparing Senate to House members or for analyzing multiple Congresses jointly. When preferences are more appropriately measured with common space scores (Poole, Keith T. 1998. Recovering a basic space from a set of issue scales. American Journal of Political Science 42:964–93), there is no evidence that the factors that she highlights matter.