This paper focuses on giving more reasonable answers to questions about whether children are better than adults in mastering the second language. This paper is based on research conducted by Steinberg in 1982 and 1993 to answer the question of how children and adults control second/foreign languages and how these barriers interfere with the level of mastery of the target language (second/foreign language). The process of obtaining second language can be from the natural/social/acquisition and from class/learning. The process of of second/foreign language mastery for adults and children may perform different outcomes. The learner's internal factors such as the role of the first language, motivation, and attitudes are also very important in determining the success of second language acquisition. It should be understood also about the pattern of the language and its productive skills after passively obtained the second language. Steinberg et al. try to draw the conclusion that the decrease in memory power for learners is associated with age. The conclusion is, when age increases ultimately affect the decline in motor skills, the learner's level of articulation will also be disrupted. Above all, many theories state that motivation or learning goals are necessary in teaching languages other than mother tongue. Age cannot be a benchmark for the success rate of mastering a second/foreign language other than mother tongue as long as the involved people have desires to use the foreign language or the second language for the purpose of integrating and socializing.