Purpose: The primordial prevention of atherosclerotic cardiovascular disease (ASCVD) involves the prevention of the onset of its risk factors. This review explores the associations between early modifiable risk factors and the development of ASCVD in adulthood, as well as evidence-based interventions to prevent them. Review Methods: A review was conducted on the basis of an in-depth literature search including longitudinal observational data, systematic reviews and meta-analyses published in 2012 or later, clinical trials, and additional manual searches of recent literature based on reference lists of other reviews and relevant guidelines. Summary: ASCVD is a disease that begins in childhood; hence, primordial prevention is an important target for improving cardiovascular morbidity and mortality later in life. Data from large-scale population studies have consistently identified the following modifiable risk factors for the development of ASCVD: smoking, overweight and obesity, high cholesterol, high blood pressure, hyperglycemia, poor diet, and physical inactivity. These risk factors originate during the prenatal, childhood, and adolescent stages of life. Various successful interventions to prevent the onset of each risk factor have been evaluated at the individual, community, and population levels. Implementation of a heart-healthy dietary pattern and regular exercise early in life are large components of many successful interventions.