Apparatuses, systems, and methods are disclosed for radio link monitoring (RLM) for unicast sidelink (SL) communications. A processor for a base station includes first circuitry configured to generate a radio resource control (RRC) message comprising an RRC information element indicating a number of unicast SL RLM reference signals. The processor includes second circuitry configured to encode the RRC message for transmission to a user equipment (UE). The processor includes third circuitry configured to generate a reference signal indicating an in-sync (IS) threshold and an out-of-sync (OOS) threshold for an RLM resource. The processor includes fourth circuitry configured to encode the reference signal for transmission to the UE. The processor includes fifth circuitry configured to transmit the RRC message and the reference signal to the UE.