The unique ability to communicate through speech clearly distinguishes human beings from all other animals. Children start to produce their first words by the age of one; by four, most children have developed the ability to use their native language; by six or seven, they become veteran users of their native language. Many studies have focused on the developmental trajectories of one or two types of phonetic units of speech (e.g., consonants, vowels, or tones), but a more comprehensive picture of speech development is still lacking. Questions deserving further investigation include: What are the order and rate of acquisition of various phonetic units? What is the possible driving force underlying the developmental order? How can we ascertain when children have obtained the same speech competence as adults? In this chapter, we will first review the literature on the development of speech perception and production in Mandarin-speaking children. Then, we will discuss relevant issues, and suggest possible solutions to the unresolved questions.