This article explores Robert E. Lucas’s policy agenda and his engagement with the public debate between the 1970s and early 1980s. It investigates how he interacted with the public debate by envisioning key principles of his macroeconomic theory and methodology, and how he promoted his policy agenda. An exploration of Lucas’s personal and professional archives sheds light on his participation in policy debates after the publication of his works, illustrating how Lucas built a discreet and cautious way of engaging with the public. Lucas did not propose a detailed program to implement his policy agenda, nor was he actively promoting his policy agenda. The article suggests that Lucas’s originality compared to his contemporaries was his belief on the ability of macroeconomics to scientifically devise binding policy rules that could be integrated in an economic constitution.