Solution-focused therapy is a client-centred and strengths-based approach that aims to support clients to recognise and describe their own strengths, skills and resources that they can use to move towards their preferred future. It is a collaborative and hopeful approach, with a focus on the role of language to enhance the change process. This research explores how agency and strengths are co-constructed through solution-focused counselling with adolescents in a New Zealand secondary school setting. It is a practice-based research project, which focuses on two case studies that include data from solution-focused counselling sessions with three participants. Data from two clients have been merged into one case study. Qualitative research methods were used to explore the process of how agency and strengths were co-constructed and experienced by both the counsellor and clients through solution-focused counselling with adolescents. Video recordings of the sessions and session transcripts provided the basis of the data, alongside researcher observations and reflections. These were analysed using narrative analysis and presented in the findings as narrative case studies. The participant’s narratives were presented in chapters of how agency and strengths were co-constructed and experienced. These were re-storied alongside session transcripts, counsellor reflections and literature to give the reader a sense of the solution-focused counselling process with each client. This wove together the voice of the clients, counsellor and the literature. The chapters of the client’s stories of agency and strengths include: Connection to self, Connection to Others, Connection to Future, Connection to What Helps, Connection to the Counselling Process, and Connection to Agency Outcomes. The discussion further ties together solution-focused literature with the findings of how agency and strengths were co-constructed. It is hoped that this practice-based research will provide a useful addition to the research on how agency is co-constructed and experienced through solution-focused counselling sessions that have a focus on strengths with adolescents.