AbstractOlder parents in China rely heavily on their adult children for instrumental assistance. In different multi-child families, multiple offspring may co-operate in providing instrumental support to older parents in distinct ways in terms of how much support they provide on average and how much differentiation exists between them when they provide such support within a family. We aimed to identify different within-family patterns in relation to multiple offspring's instrumental support to an older parent in Chinese multi-child families, and to investigate potential predictors for different within-family patterns. Using data from the China Family Panel Studies (2016), we had a working sample of 5,790 older adults aged 60+ (mean = 68.54, standard deviation = 6.60). We employed latent profile analysis (LPA) to classify within-family patterns and multinomial logistic regression to investigate predictors. Our findings identified three within-family patterns: dissociated (59.10%), highly differentiated (29.60%) and united-filial (11.30%). Older parents in the highly differentiated families tended to be older, mothers, divorced/widowed and to have poorer physical health compared to their counterparts in the dissociated families. In contrast, the composition characteristics of multiple adult children played more important roles in determining the united-filial within-family pattern. The united-filial families were more likely to have fewer adult children, at least one adult daughter and at least one co-residing adult child.