Despite increased interest in the quality of life of younger populations, the quality of life of youngsters in vulnerable situations such as those in youth services remains under-researched. To gain insight into critical ingredients for understanding and enhancing the lives of these youngsters, appropriate assessment tools are needed. This study focuses on providing content-related validity evidence for the new Quality of Life in Youth Services Scale (QOLYSS) for adolescents in youth services. A sequential approach to item generation, refinement, and evaluation is presented. The initial item bank is devised by means of a thorough literature search and evaluated against findings from qualitative research among adolescents in youth services. In addition, a three-round international expert panel (N = 5) is convened to align identified items to the adopted quality of life framework, and to provide evidence on domain representation and relevance. Last, input is collected from adolescents in youth services themselves. More specifically, 20 group discussions and 13 individual interview sessions are organized to support 21 adolescents in critically assessing the content of the item bank on level of relevance, clarity, and coverage. The expert panel resulted in a provisional scale of 262 unique items that, based on adolescents’ input, is further reduced to a set of 88 items. Adolescents omitted items because of divergent reasons (e.g., content-overlap, self-evident character of the items, level of irrelevance). Explanatory qualitative information on the item selection process is provided. This study provides a detailed understanding of the content-related validity evidence of a new multidimensional quality of life scale. Moreover, it highlights the importance of acknowledging youngsters as critical partner in quality of life research and assessment.

尽管人们对年轻人口的生活质量越来越感兴趣，但是，处于脆弱境况的青年人（例如青年服务机构）的生活质量仍在研究中。为了深入了解了解和改善这些年轻人的生活的关键要素，需要适当的评估工具。这项研究的重点是为青少年服务青少年的新生活质量量表（QOLYSS）提供与内容相关的有效性证据。提出了一种用于项目生成，细化和评估的顺序方法。最初的项目库是通过全面的文献搜索而设计的，并根据青少年服务中青少年定性研究的结果进行评估。此外，由三轮国际专家小组（N = 5）召开会议，以使已确定的项目与所采用的生活质量框架保持一致，并提供有关域表示形式和相关性的证据。最后，从青少年中收集青少年服务本身的投入。更具体地说，组织了20次小组讨论和13次个人访谈，以支持21名青少年就相关性，清晰度和覆盖程度进行批判性地评估项目库的内容。专家小组得出了262个独特项目的临时量表，根据青少年的投入，该量表进一步缩减为88个项目。青少年由于各种原因（例如内容重叠，项目的不言而喻的程度，不相关的程度）而忽略了项目。提供有关项目选择过程的解释性定性信息。这项研究对新的多维生活质量量表的与内容相关的有效性证据提供了详细的了解。此外，它强调了承认年轻人为生活质量研究和评估的关键伙伴的重要性。