With the rise of exemplar theory, the role of lexical frequency in language variation has been the object of considerable study. Recently, Erker and Guy (2012) extended the analysis of frequency to morphosyntactic variation and examined the role of frequency in variation between null and overt subject personal pronouns (SPPs) in Spanish. Their results suggest that frequency either activates or amplifies the effects of other constraints, such as co-reference. This study extends the study of frequency effects on SPP variation to Mandarin Chinese. Results of multivariate analysis of 6,691 tokens collected from Mandarin speakers in Harbin, China indicate that the effect of frequency on Chinese SPP variation is less than that of other well-established constraints such as co-reference and person and number. The results suggest that the role of frequency in this area of the grammar has been considerably exaggerated. Rather, well-established linguistic constraints provide a better explanation for SPP variation than frequency.