Described are methods, apparatus and computer programs for determining run-time dependencies between logical components of a data processing environment. Components of the data processing environment are monitored by monitoring agents accessing run-time activity data via APIs of the managed system. A dependency generator identifies correlations between the run-time activity of the monitored components. For synchronous monitored systems, the dependency generator calculates an activity period for monitored components and determines which component's activity periods contain the activity periods of other components. Containment is used as an indicator of a likely dependency relationship, and a weighting is computed for each dependency relationship based on the consistency of containment.