Mainstream Second Language Acquisition research on socio-affective factors has largely relied on self-reported psychological variables, often overlooking the complexity of learners' affective experiences. This book addresses this gap by examining how socio-affective factors shape English as an Additional Language (EAL) speech performance in a Brazilian context. Drawing on learners' autobiographies, instructor evaluations, and classroom observations, the study investigates how personal narratives inform learners' affective regimes and relate to speech attainment. Grounded in McAdams and Pals' New Big Five framework, the research develops an integrative model of socio-affective factors in EAL learning. Findings suggest that learners with higher speech attainment share positive cultural beliefs, enjoyment of language learning, satisfaction with instruction, and similar individual difference profiles, including high willingness to communicate. The study also reveals that high-performing learners tend to underestimate their oral proficiency. By offering a nuanced understanding of the relationship between affect and speech achievement, this book provides valuable insights for researchers and language educators seeking to better understand learner success and performance variation.