The present study adopted Articulatory Phonology as a theoretical framework to investigate the aticulatory timing of English consonant clusters. Both native and non-native (Mandarin ESL learners) speakers’ performances were of interest. An acoustic approach was taken to explore the consonantal overlap in both native and non-native English speakers’ production. Also investigated in the present study were the factors that influence the overlap between consonants. Thirty-one native Mandarin speakers and eight native Canadian English speakers participated in the study. The thirty-one native Mandarin speakers were divided into three proficiency groups according to a pretest which evaluated Mandarin speakers’ English speaking proficiency. The experiment of the study was a reading task. Participants were instructed to put the words ending with the target consonant clusters in four carrier sentences and read them aloud. In total, 256 tokens (20 clusters×2 vowel environments×4 carrier sentences+12 consonants×2 vowel environments×4 carrier sentences) were recorded for each participant. The duration of each segment in the word was measured in the phonetic software, Praat. Three timing ratios: consonant to cluster, cluster to a pair of individual consonants, and cluster to rime were calculated. Repeated measures ANOVAs showed significant effect for place of articulation and manner of articulation on the articulatory timing of English consonant clusters in the coda position. Meanwhile, voicing feature, as an unexpected factor, was also reported to be an influential factor. More detailed analysis revealed that heterorganic clusters have more overlap than homorganic clusters. Within heterorganic clusters, a tongue tip consonant is more overlapped by a following tongue body consonant than a tongue body consonant is by a following tongue tip consonant. For manner of articulation, stops are found to be more overlapped by a following stop than by a following fricative. Overlapping caused by voicing feature was an unexpected outcome found in the present study. Voiceless consonant clusters have more overlap than voiced clusters. The difference between native and non-native speakers is also of interest. With respect to the amount of overlap, native speakers have more overlap than non-native speakers. Moreover, statistic tests reported a significant effect for proficiency group. From the comparison of mean values of three ratios, the performance of advanced group was close to native speakers. And intermediate and low groups exhibited similar performance. / Graduate