Makassar City is one of the marketing centers for various kinds of fishery products, both raw material-based and processed. Changes in the lifestyle of the people of Makassar City affect the food consumption patterns of the community. Makassar City residents are interested in instant food products that are durable and easy to serve. This study aimed to analyze the effect of product knowledge on product familiarity, social environment on product familiarity, product knowledge on purchasing decisions, social environment on purchasing decisions, product familiarity on purchasing decisions, product knowledge on purchasing decisions through product familiarity and social environment on purchasing decisions through product familiarity. This research was conducted in Makassar City.  Data collection used an accidental sampling method with a questionnaire. The sample consisted of 384 consumers. The data were processed using Smart PLS Version 4.0. The results indicate that product knowledge has a significant effect on product familiarity. Similarly, the social environment significantly affects product familiarity. Product knowledge also significantly influences purchasing decisions, as does the social environment. Additionally, product familiarity has a significant effect on purchasing decisions. Product knowledge influences purchasing decisions through product familiarity, and the social environment also impacts purchasing decisions through product familiarity in the context of frozen processed fish food products.