External factors refer to the factors existing outside the learners but which influence the development of learners’ language acquisition. Since such influence usually emerges from the environment where the learners live, those are also referred to as environmental factors. What could be influential on learners’ language skill development and in what ways those factors affect language ability will be dealt with in this paper. As a conceptual paper, this article is written based on the writers’ knowledge, beliefs, and experiences intertwined with their understanding of psycholinguistic theories obtained from various resources. It is claimed that various external factors that might have impacts on the acquisition and improvement of learners’ language competence can be addressed to both formal and natural environments that are manifested in terms of linguistic input that abundantly exists and is frequently exposed comprehensibly to the learners. These ideas are useful to be taken into consideration and may have implications on the practice of language teaching and learning, especially in promoting effective language acquisition.