This article examines the building of Communist surveillance networks in Czechoslovakia and Poland in the early 1950s, focusing on the methods employed by the operational divisions of the secret police in these countries and their system of "preventative policing," and shows how the secret police networks shaped the information reaching Communist party leaders and Soviet advisers in East-Central Europe during the Stalinist period. By examining how the regimes collected information on the economy, religious institutions, higher education, and other areas of everyday life, the article traces how blanket surveillance networks became more institutionalized, insular, and scripted over time, hindering the state's ability to collect and process meaningful information. These problems were symptomatic of larger informational barriers facing Soviet-style regimes.