Service design determines the success of a business operation. How to identify customers’ needs and design high-quality services are important issues. Persona has been   adopted   as a   tool  for   identifying   needs   of individual   users   for   service   design. Its   focus   on individual  needs  reveals  its  limitations  in  failing  to capture the interactions among individuals. This study proposes a new user-needs assessment method, named Groupsona, to identify  individual  customer’s  social needs of interacting with  other members  in the group. Groupsonas are  group archetypes that represent   customers’   needs based   on   the   group’s perspectives  and  the  interactive  behaviors  of users in the    group. Based    on    concepts  of  constructing egocentric   network in  Social  Network   Analysis, Groupsona  provides  a  tool  for  recognizing  network patterns and understanding the various ways of group interactions. We applied Groupsona to analyze weight loss  group  members’  needs.  The analytical  results showed   Groupsona can represent  and identify the characteristics of customers’ needs.