Long before he was mashing home runs and making a name for himself as a professional, Mark Vientos was doing the same as a teenager, establishing his name on the exhibition and showcase circuit and earning praise from scouts and evaluators as early as 2013, when he was just 14 years old. For three years, he played ball at Charles W. Flanagan High School in Pembroke Pines, Florida, but in 2016, he switched schools and began attending American Heritage High School in Plantation, a few miles south. Vientos only appeared in 26 games for the American Heritage High School Patriots, missing some time in the spring due to a quad injury, but he made his time on the field count, hitting .