Background: There is an absence of studies exploring different goal-setting appraches and none which have examined the use of proxy goal-setting by parents for their children. Aim: To explore how proficient parents are in setting health behaviour goals for their children according to SMART (specific, measurable, achievable, realistic and time-framed) goal principles. A secondary aim was to examine associations between goal setting and change in health behaviors. Methods: Participants were parents and children taking part in one of two trials incorporating goal setting. Study 1 ( Time2bHealthy) was an online program for parents of preschoolers ( n = 36) and Study 2 ( HIKCUPS) was a three-arm face-to-face trial examining a parent-centered dietary intervention, (Study2Diet); a child-centered physical activity intervention, (Study2PA); or combination of both (Study2Combo) ( n = 83). Goals were coded on five ‘SMART’ principles. Goals were scored 1 or 0 for each principle (1 indicated the principle was met and 0, not met). The total maximum score for each goal was 5. Mean total goal-score and means for each SMART principle were calculated. Results: Mean (and standard deviation) goal setting scores for Study 1 were 3.84 (0.61), Study2Diet 2.17 (1.33), Study2PA 3.18 (1.45) and Study2Combo 2.24 (1.30). Goal-scores were significantly higher for Study 1 than Study 2 ( p < 0.001). In Study2Diet, goal setting was significantly associated with greater reduction in energy intake ( p = 0.019). Conclusions: Goal-scores were highest in Study 1, which used a supported online format for setting goals. Parents were better at setting physical activity goals, but these goals did not translate into improvements in physical activity behavior. Goals set by parents may be useful in energy intake reduction, however further research is required to determine benefits for weight status or physical activity.