This study aims to increase the use of virtual reference service by increasing the awareness of the availability of the service to users who really need it. A new situationally-based virtual reference interface, called the sVR interface, has been designed to reflect different levels of user search success. Findings from an eight-month field study done in a university library improved our understanding of how to effectively enhance the availability of virtual reference service to users who need it. A discussion about balancing the availability and the intrusiveness of virtual reference service is also provided.