Many prevention and countering of violent extremism experts place too much emphasis on the radicalising power of online mass distributed messaging by violent extremist groups. Instead, Nafees Hamid argues that radicalisation takes place in a social ecology within which the messaging of terrorist groups plays only a small role. This article shows that people are resistant to mass persuasion and that certain environments are more conducive to the spread of extremist messaging. Small-group dynamics are useful to explain the spread of ideas and that altering these dynamics can provide a buffer against some ideas while enabling others.