What characterizes European Union soft law and what are its implications for the EU multilevel system? What is the proportion of hard and soft law in EU policy? Which types of soft law act are adopted in different policy sectors? This article introduces the conceptual and analytical framework that encompasses the EfSoLaw dataset and explains its methodology, advantages, and limitations. This dataset unites information on thousands of EU hard and soft law acts from seven different policy sectors, drawn from over fifteen years (2004–2019) and from various sources (EUR-Lex, DGs, agencies). We present implementation options of the dataset making it exploitable for other scholars and we propose hypotheses to explain the variation in the adoption of soft law in different policy sectors.