It has been widely accepted that parental language beliefs play a crucial role in language maintenance. Studies show that Chinese immigrants are not exempted from language shift although they are frequently reported cherishing their language as an important part of their culture. This paper attempts to find out how parental language beliefs reflect their daily language behaviour. Eight recent Chinese migrant families had 60 minutes of conversation recorded each month for one calendar year. Their language use has been analyzed and compared with the information gathered from a home language use questionnaire. Results show that there is a substantial gap between parental language beliefs and their actual language behaviour. Although the parents state they strongly support mother tongue maintenance, within 28 months, the use of mother tongue had dropped significantly and there is very little evidence showing much effort from the parents to prevent this from happening. This could be either because they want their children to keep their first language but do not know how to do this, or, their language beliefs are different from their behaviour. This should raise methodological issues regarding how to interpret parental language beliefs properly in the research area.