This study concerns the simultaneous acquisition of conditional constructions in Chinese-English bilingual preschool children in Singapore. Cross-sectional data were obtained from subjects ranging from 2;10 to 6;06. The target languages are Singapore Colloquial English (SCE) and Singapore Colloquial Mandarin (SCM), both of which are contact varieties that are representative of the Low varieties in a diglossic situation. The bilingual acquisition of structural features of conditionals was investigated by adopting the Head-marking and Dependent-marking typological framework (Nichols 1986).