Open Source Software for Social Good (OSS4SG) projects aim to address critical societal challenges, such as healthcare access and community safety. Understanding the community dynamics and contributor patterns in these projects is essential for ensuring their sustainability and long-term impact. However, while extensive research has focused on conventional Open Source Software (OSS), little is known about how the mission-driven nature of OSS4SG influences its development practices. To address this gap, we conduct a large-scale empirical study of 1,039 GitHub repositories, comprising 422 OSS4SG and 617 conventional OSS projects, to compare community structure, contributor engagement, and coding practices. Our findings reveal that OSS4SG projects foster significantly more stable and "sticky" (63.4%) communities, whereas conventional OSS projects are more "magnetic" (75.4%), attracting a high turnover of contributors. OSS4SG projects also demonstrate consistent engagement throughout the year, while conventional OSS communities exhibit seasonal fluctuations. Additionally, OSS4SG projects rely heavily on core contributors for both code quality and issue resolution, while conventional OSS projects leverage casual contributors for issue resolution, with core contributors focusing primarily on code quality.

翻译：面向社会公益的开源软件项目致力于解决医疗可及性、社区安全等关键社会挑战。理解这类项目的社区动态与贡献者模式，对于确保其可持续性与长期影响力至关重要。然而，尽管现有研究广泛聚焦于常规开源软件，但关于OSS4SG项目的使命驱动特性如何影响其开发实践，目前仍知之甚少。为填补这一研究空白，我们对1039个GitHub代码库（包括422个OSS4SG项目和617个常规OSS项目）开展了大规模实证研究，以比较其社区结构、贡献者参与度及编码实践。研究发现：OSS4SG项目培育的社区显著更为稳定且具有“粘性”（63.4%），而常规OSS项目则更具“磁性”（75.4%），吸引着高流动率的贡献者。OSS4SG项目在全年度均保持稳定的参与度，而常规OSS社区则呈现季节性波动。此外，OSS4SG项目高度依赖核心贡献者来保障代码质量并解决问题，而常规OSS项目则利用临时贡献者解决问题，其核心贡献者主要专注于代码质量。