This paper defines quasi-coresidence, a type of living arrangement in Southeast Asia in which parents and children live separately but in close proximity and see and help one another frequently. Since this is a new concept that has not been previously researched, the authors consider a number of alternative measures of quasi-coresidence, including the frequency with which adult children visit their mothers, provide assistance to their mothers, or both visit and assist their mothers. Using data from the Second Malaysia Family Life Survey, the authors find that frequent visits between children and mothers are very common among all ethnic groups in Peninsular Malaysia and that frequent assistance, although more rare than visits, is also fairly prevalent. For example, among mothers who do not coreside with an adult child, more than 8 percent receive both weekly assistance and weekly visits from at least one of their children. Whereas Malays (particularly sons) are less likely to coreside with mothers, they are more likely to provide assistance when they do not coreside. The authors also find other evidence of substitution between coresidence and quasi-coresidence.