Child acquisition of Mandarin was studied with four middle class families from Taipei, Taiwan. The 2-year-olds were taped at home playing with their families. Two of the children were taped for short periods (7 hours and 9 hours), while the other two children were studied biweekly for 14 months, which resulted in 71 hours of transcribed child tapes as well as 3 hours of adult control data. All four unacquainted children showed strikingly similar language acquisition strategies. Word class categorizations and word order are discussed in detail, using examples of the children's speech. Although Chinese selectional restrictions have few surface indicators, Chinese children regularize and double mark the linguistic relations. Their innate capacity for grammatical marking by word order and morphology is stronger than required by the language they are learning. In terms of word class categorizations, the children seem to illustrate classical Chinese grammar and philology by first assuming that all morphemes are full, free, unbound forms, equivalent to lexically full words. It is concluded that Mandarin is comparable to European languages in difficulty and rate of acquisition, as well as in the amount of experimentation and error required to master it. (SW)