This paper is concerned with young people's perceptions and reported use of the two language varieties that co-exist in the urban centre of Guangzhou in southern China, Putonghua (P) and Cantonese (C). P is a typical H-variety, promoted by the government and used as a lingua franca throughout China; C is the local L-variety but it also has some prestige and is used in all domains. The focus of our questionnaire study was twofold: to analyse possible gender differences in perceptions and reported use, and to compare results from P-speaking newcomers, who have moved to Guangzhou from other parts of China, with responses from local C-speaking adolescents. Our results suggest that Guangzhou is a reasonably stable diglossia where P and C serve different functions, for newcomers as well as locals, and therefore both varieties appear to be indispensable. However, there are also indications that P promotion is beginning to have an effect in Guangzhou; our female participants seem to be leading on in a gradual change towards increased use of P. Thus our results support the trend reported in numerous sociolinguistic studies of a female preference for the prestige standard variety of a language.