Young children under 8 years old are viewed as especially vulnerable to marketing communications because they do not have sufficient knowledge about the purpose of persuasive advertising messages, also known as children's persuasion knowledge (CPK). However, a review of 25 studies that have tested CPK effects, on primarily older children, finds inconsistent or no support for CPK. The lack of support depends on the effect studied, and a measurement challenge because of young children's limited capabilities in reading and responding to questions from interviewers. Thirteen measures of CPK have been tested but not compared for CPK effects. These measures were simplified to nonverbal options for young children and tested on a sample of 4‐ to 7‐year‐old North East Chinese children (n = 233). These measures were each tested in relation to the children's age (positive), their skepticism toward advertising (positive), their disbelief of false claims in a TV commercial (TVC) (positive) and their affect toward the TVC (negative). Only two measures of CPK show any expected associated responses with “knowing the source” of advertisements the best measure. Perceived marketer intentions had no expected associations, nor did the age of the child. The implications of these findings are discussed in terms of theory, measurement, and applications for marketers and public policy.