This paper provides an original theoretical framework to better understand the raise of private standards in agrifood chains. Reasons for the emergence and conditions for the effectiveness of private standards are identified, by investigating retailers' strategic behaviour and, more precisely, both interactions among retailers and upstream producers and the role of consumer behaviour vis-àvis the food safety risk. We show that a relatively strict Minimum Quality Standard (MQS) may incentive the retailer to develop an even more demanding private standard, when market-driven incentive is relatively high; this result crucially depends on consumer risk misperception. Setting a private standard may improve market access for upstream producers. In addition, it may reduce food safety risk and, at the same time, improve consumer surplus.