Phonological perception and processing is not only important in spoken language recognition and comprehension,but also important in the development of reading ability.This review paper examined phonological perception and processing in a second language(L2 )among infants,school-aged children,and adults.Infants are born with the ability to discriminate universal sets of phonetic distinctions,but this ability may decline or be lost later on due to lack of corresponding linguistic experience.For both children and adults,their L2 phonological processing skill is influenced by their L1 knowledge and not only L1 phonology but also the orthography impacts the L2 phonological processing.L1 phonological skills contribute to the development of L2 reading skills over and above the within-L2 phonological skills.Limitations and future research direction are discussed. Phonological perception and processing is not only important in spoken language recognition and comprehension, but also important in the development of reading ability. This review paper examined phonological perception and processing in a second language (L2) among infants, school-aged children, and adults .Infants are born with the ability to discriminate universal sets of phonetic distinctions, but this ability may decline or be lost later on due to lack of corresponding linguistic experience. For both children and adults, their L2 phonological processing skill is influenced by their L1 knowledge and not only L1 phonology but also the orthography features the L2 phonological processing. L1 phonological skills contribute to the development of L2 reading skills over and above the-L2 phonological skills. Limits and future research direction are discussed.