Some of you will have heard of plain old cognitive therapy (CT) and rational emotive therapy (RET), dating back to the pathbreaking work of Aaron Beck and Albert Ellis. Most of you will have heard of cognitive behavioral therapy (CBT), an enhancement of cognitive therapy alone (and why RET later became REBT). But I suspect many fewer readers know as much about acceptance and commitment therapy (ACT—proponents prefer it to be pronounced ‘act,’ not ‘A‐C‐T’), a newer kid on the block but growing rapidly, and with an extensive research base. What is it and how does it add to our therapeutic armamentarium?