A conversational agent is provided for maintaining or improving the wellbeing of a user presenting with mental health needs by the delivery of a care protocol. The conversational agent comprises: a plurality of sub-dialogue units, each configured to deliver an element of the care protocol, and an orchestrator configured to present the sub-dialogue units to the user, sequentially, wherein each sub-dialogue unit and the orchestrator comprises: a natural language understanding module configured to receive an input and/or reply and determine at least one intent and, where present, at least one slot within the input and/or reply; a dialogue planning module configured to determine an output based, at least in part, on the at least one intent and/or slot associated within the input and/or reply, and a natural language generation module configured to provide the output to the user.