During the late 1950s and 1960s period historians and collectors call the Silver Age of Comic Books, Sinnott continued doing occasional pencil-and-ink stories for Atlas Comics as it transitioned into the nascent Marvel Comics, contributing to such "pre-superhero Marvel" titles as "Strange Tales", "Strange Worlds", "Tales to Astonish", "Tales of Suspense" and "World of Fantasy". He also began a stint with the low-budget Charlton Comics, teamed as penciler with inker Vince Colletta on several romance-comics stories in series including "First Kiss", "Just Married", "Romantic Secrets", "Sweethearts" and "Teen-Age Love" that he would do through 1963.