Purpose: The aim of this study was to investigate children's acquisition of Vietnamese speech sounds. Method: Participants were 195 children aged 2;2-5;11 (years;months) living in Northern Viet Nam who spoke Vietnamese as their 1st language. Single-word samples were collected using the Vietnamese Speech Assessment (Ph?m, Le, & McLeod, 2016) to measure accuracy of consonants, semivowels, vowels, and tones. Results: Percentage of consonants correct for children aged 2;0-2;5 was 46.39 (SD = 7.95) and increased to 93.13 (SD = 6.13) for children aged 5;6-5;11. The most difficult consonants were /palatal nasal, s, z, x/. Percentage of semivowels correct for children aged 2;0-2;5 was 70.74 (SD = 14.38) and increased to 99.60 (SD = 1.55) for children aged 5;6-5;11. Percentage of vowels correct for children aged 2;0-2;5 was 91.93 (SD = 3.13) and increased to 98.11 (SD = 2.79) for children aged 5;6-5;11. Percentage of tones correct for children aged 2;0-2;5 was 91.05 (SD = 1.42) and increased to 96.65 (SD = 3.42) for children aged 5;6-5;11. Tones 1, 2, 5, and 6 were acquired by the youngest age group, whereas Tone 3 (creaky "thanh ngã") and Tone 4 (dipping-rising "thanh h?i") did not achieve 90% accuracy by the oldest age group. Common phonological patterns (> 10%) were fronting, stopping, deaspiration, aspiration, and semivowel deletion for children aged 2;0-3;11 and were fronting and deaspiration for children aged 4;0-5;11. Conclusion: This is the 1st comprehensive study of typically developing Northern Vietnamese children's speech acquisition and provides preliminary data to support the emerging speech-language pathology profession in Viet Nam.