He did staff work in the Netherlands until 1942 under Nazi occupation, when he assumed the name Joost (instead of the more Jewish-sounding Abraham) to fool the occupying forces.

He was the author of many books, including Rape of the Mind (a classic work on brainwashing), Conversation and Communication, and Hidden Communion.

He subsequently married Louisa Betty "Loekie" Duits, a physical therapist, in New York City on May 7, 1948.

This book received wide attention in part because it dealt with totalitarian applications of brainwashing techniques during the Korean War.

People must guard against the creeping intrusion into their minds by technology, bureaucracy, prejudice, and mass delusion.

Meerloo writes that freedom and democracy depend in part on education for mental freedom—helping children and adults to think for themselves and to see the essentials of a problem—helping them to understand concepts, not merely to memorize facts.

However, he also attacks the witch-hunting of individuals through the House Un-American Activities Committee: "the Congressional right to investigate can be abused and misused.