  We introduce a novel application of large language models (LLMs) in
developing a virtual counselor capable of conducting motivational interviewing
(MI) for alcohol use counseling. Access to effective counseling remains
limited, particularly for substance abuse, and virtual agents offer a promising
solution by leveraging LLM capabilities to simulate nuanced communication
techniques inherent in MI. Our approach combines prompt engineering and
integration into a user-friendly virtual platform to facilitate realistic,
empathetic interactions. We evaluate the effectiveness of our virtual agent
through a series of studies focusing on replicating MI techniques and human
counselor dialog. Initial findings suggest that our LLM-powered virtual agent
matches human counselors' empathetic and adaptive conversational skills,
presenting a significant step forward in virtual health counseling and
providing insights into the design and implementation of LLM-based therapeutic
interactions.
