--- - |2 In many countries, the law permits state authorities to detain noncitizens before deportation. Typically judicial decisions about preremoval detention must be made within a short period of time during which deportable noncitizens are held in police premises, and depending on the country detention may last just one month (e.g., France) or up to 18 months (the Netherlands). While previous research has explored various dimensions of noncitizen detention including the legal procedure, health consequences, the condition of detention centers, and the lives of deportable noncitizens, the empirical assessment of the determinants of decisions on preremoval detention are largely unexplored. Using data from court proceedings of police petitions of detention in Spain and a quantitative strategy, in this article we undertake an empirical analysis of noncitizen detention combining personal background of deportable noncitizens, legal factors of the case, and the behavior of different actors involved in the procedure. To do it, we fit models that take into account variation occurred at judicial district levels. Results indicate, on the one hand, that relevant actors involved in the procedure use different informational cues to decide on cases. On the other hand, the role of prosecutors and attorneys during hearings proves also relevant to predict detention. - 'Law &Society Review, Volume 53, Issue 3, Page 740-763, September 2019. '