This chapter focuses on an empirical study that was conducted with a small sample of young English learner (EL) and non-EL students who participated in one of the prototyping studies undertaken as part of the TELP project. It examines performance differences between the young EL and non-EL students on speaking tasks. Because the TELP prototype tasks were designed to distinguish between EL and non-EL students, the project paid special attention to collecting the performances of both native English speakers and ELs. The chapter provides the characteristics of young children that should be considered when designing assessment tasks. It discusses the major findings of the comparative analyses between the linguistic performances of EL and non-EL students, focusing on the speaking tasks. The chapter further provides error analysis as a potential way to reveal the language developmental patterns of young children.