He sold his first story in 1938 to the McClure Syndicate, which bought much of his early (non-fantastic) work; his first genre appearance was "Ether Breather" in "Astounding Science Fiction" a year later. At first he wrote mainly short stories, primarily for genre magazines such as "Astounding" and "Unknown", but also for general-interest publications such as "Argosy Magazine". He used the pen name "E. Waldo Hunter" when two of his stories ran in the same issue of "Astounding". A few of his early stories were signed "Theodore H. Sturgeon."