This chapter addresses three questions about the relationship between political discourse and action: Do political parties keep their promises once elected? What are the methodologies used by scholars to demonstrate that political parties keep (or do not keep) their campaign promises? Are these methodologies valid and reliable? We answer these questions based on a review of 18 journal articles and book chapters published in English and French over the past forty years that report quantitative measures of election promise fulfillment in North America and Europe. We find that parties fulfill 67% of their promises on average, with wide variation across time, countries, and regimes. Most Studies have major methodological weaknesses (no operational definition, no mention of relevant documentation, flawed research design) although the more recent ones tend to show higher levels of methodological sophistication and a modicum of scientific transparency.