Abstract
Purpose Citizen engagement plays a crucial role in transitioning to sustainable service ecosystems. While customer engagement has been extensively studied in service research, citizen engagement has received significantly less attention. By synthesizing customer and citizen engagement literatures, this study develops an integrated framework to conceptually clarify the dual role of customer-citizen engagement for sustainability. Design/methodology/approach This study builds on a systematic literature review of customer engagement literature in service research and citizen engagement literature. Following a theory synthesis approach, we qualitatively analyzed 126 articles to develop an integrated conceptual framework of customer-citizen engagement for sustainability through a process of abductive reasoning. Findings The analysis showed that customer engagement and citizen engagement literatures have developed mostly separately but provide complementary views. While the customer engagement literature has traditionally focused on business-related facets, such as engagement with brands, the citizen perspective broadens the engagement scope to other citizens, communities and society in general. The integrated framework highlights the interplay between citizen and customer roles and the impact of their relationships with multiple objects on sustainability. Originality/value This integrated framework contributes to advancing our understanding of customer-citizen engagement, broadening the scope of subject-object engagement by examining the interplay between these roles in how they engage for sustainability and moving beyond the traditional dyadic perspective to a multi-level perspective of service ecosystems. This framework also enables the development of a set of research directions to advance the understanding of engagement in sustainable service ecosystems.

Abstract
Engagement in the ongoing energy transition is particularly challenging for energy-poor citizens. As such, there is a pressing need for a better understanding of their experiences and for strategies that enable their engagement. In this study, we identify different groups of citizens based on their energy poverty issues and examine their engagement behaviors (seeking information, proactive managing, sharing feedback, helping others, and advocating). Using cluster analysis and multiple correspondence analysis, we analyzed a sample of 915 citizens from eight European cities participating in a Horizon2020 EU project (Alkmaar-NL, Bari-IT, Celje-SI, Evora-PT, Granada-ES, Hvidovre-DK, Ioannina-GR, & Uacute;jpest-HU). Several groups of citizens reported either multiple energy issues, a single issue (energy bills, insulation, cooling, heating), or no issues, and the statistical tests showed significant differences across these groups in terms of engagement in seeking information, helping, and advocating. Moreover, we identified that certain groups tend to have specific levels of engagement (high, medium, low) and that sharing feedback generally has a low level of engagement. Overall, this study provides empirical insights into how energy-poor citizens exercise agency through engagement behaviors and offers actionable insights for designing measures to mitigate energy poverty in complementarity with technical and economical solutions.