Purpose: The authors of the study sought, through a meta-analysis of primary studies, to same for those who receive a measles, mumps, and rubella (MMR) vaccination and those who do not?” Background: Despite evidence from numerous sources failing to demonstrate consistent evidence of ASD diagnoses as a consequence of receiving MMR vaccinations, parents/guardians sometimes forego vaccinating their children. Methods: Three researchers searched for and obtained relevant studies, and two researchers independently applied a standardized data extraction form to the included studies. Results: Seven independent effect sizes were calculated, yielding a pooled random-effects OR* = 0.25 (95% CI, LL = 0.09, UL = 0.76) (*denotes random-effects estimate). Under the fixedeffect model, the OR = 0.33 (95% CI, LL = 0.25, UL = 0.45). Conclusions: The odds of ASD diagnoses attributable to receiving or not receiving an MMR vaccination are not indistinguishable within clinical limits of indifference. Even so, the odds of ASD diagnoses are substantially smaller for those receiving an MMR vaccination than for those who do not.