This article presents the history of for-profit mobility from communist Poland, that is, transnational labor migrations and the movement of cross-border petty traders. On the basis of primary research in archives and new scholarship on the history of communist Poland, it presents the scale and dynamics of cross-border movements since the partial opening of the borders in the mid-1950s to the final erosion of the communist regime in 1989. It analyzes the main factors and patterns of the expansion of mobility in both its legal and irregular streams, including the relevant policies of the Polish government and the governments of migrants' destination countries, the mechanisms of the gray and black markets, especially of hard currencies, and the development and diffusion of social practices of migration. It argues that for-profit mobility was a large part of the second economy as well as a form of disengagement from the communist state and its first economy, a way of selective opting out of socialism. Analyzing the relations between its expansion and the evolution of the communist regime, the article claims that for-profit mobility produced un-communist social spaces and was an important factor eroding the regime's legitimacy and control over its subjects, thus paving the way to the post-1989 stage of Poland's transformation.