English, a second language for most people in the world,has increasingly become the international language for businessand commerce, science and technology, and internationalrelations and diplomacy. Therefore as children will soon beexpected to thrive in the global environment of the 21st century,they are forced or encouraged to start second language learning atan early age. This brings challenge to educators, because younglearners are definitely different from adults or adolescent learnersin many aspects. In dealing with younger learners, educatorsshould provide an optimal learning environment, which at leastincludes appropriate linguistic input and appropriate languageinstruction, based on the cognitive and psychologicalcharacteristics of young learners. This paper will review some theoretical assumptions whichhave implications for SLA of young learners, consider thespecific features of young learners, and provide some suggestionsfor language instruction and material design.