This document discusses factors that influence success in second language acquisition. It identifies seven key factors: social context, social experience, the relationship between first and second languages, age, aptitude, motivation, and instruction. Younger learners have an advantage in brain plasticity, while older learners have advantages in learning capacity and analytic ability. Aptitude predicts success but is not deterministic, while motivation determines effort and desire which impact proficiency levels. Quality instruction using various teaching methods makes a difference, especially in formal learning contexts.