Systems for detecting contact between an electrode and a patient's skin using one or more contact detection schemes are provided. An example system can include an electrode assembly comprising at least one electrode configured to be disposed substantially proximate to the patient's skin and configured to at least one of sense an ECG signal of the patient and provide one or more therapeutic pulses to the patient, one or more sensors disposed on the electrode assembly and isolated from the electrode, the sensors configured to measure one or more properties to determine contact between the electrode and the patient's skin, and a controller configured to receive data representing the measured one or more properties and determine, based at least in part on the received data, whether the electrode is in contact with the patient's skin. The sensors can include temperature, impedance, capacitance, optical, and other similar sensors.