External factors: social factors 

 Social demand 

 Language policy

The language policy of the government and the attitude of the public setor toward a language affect the learners of the language.

Internal factors: learner factors 

 Motivation

  Instrumental motivation

  Integrative

  Cognitive motivation (resultant motivation): the idea that the learners have a sense of achievement as long as they learn is of vital importance.

Learners who are integratively motivated are more likely to be successful, because they are psychologically prepared to adopt various aspects of the behavior which characterizes members of another linguistic-cultural group, or even eventually to become a member of that group. 

 Age

The “critical period” hypothesis states that there is a period when language acquisition takes place naturally and effectively. It was believed that the optimal age falls within the first ten years. The hypothesis was based on two assumptions: 1) the neurological basis of language in children is different from that in adults; 2) children outperform adults in all aspects of second language acquisition. Whether the former is valid remains an issue, but the validity of the latter has been challenged by later studies.

 Learning strategy

Learning strategies are the particular approaches or techniques that learners employ to try to learn a second language, especially in solving specific problems they encounter.

Cognitive strategies: or guessing meaning from context;

Metacognitive strategies: directing attention to the learning task, monitoring and evaluating learning.

Successful learners use more strategies than unsuccessful learners. Successful learners pay attention to both and form. They are more active and selective in using strategies.