Developing correct concurrent software is challenging. Design errors can result in deadlocks, race conditions and livelocks, and discovering these is difficult. A serious obstacle for an industrial uptake of rigorous analysis techniques such as model checking is the learning curve associated to the languages — typically temporal logics — used for specifying the application-specific properties to be checked. To bring the process of correctly eliciting functional properties closer to software engineers, we introduce PASS, a Property ASSistant wizard as part of a UML-based front-end to the mCRL2 toolset. PASS instantiates pattern templates using three notations: a natural language summary, a μ-calculus formula and a UML sequence diagram depicting the desired behavior. Most approaches to date have focused on LTL, which is a state-based formalism. Conversely, μ-calculus is event-based, making it a good match for sequence diagrams, where communication between components is depicted. We revisit a case study from the Grid domain, using PASS to obtain the formula and monitor for checking the property.