Cognitive distortions (or ‘unhelpful thinking styles’) are ways that our thoughts become biased. Different cognitive biases are associated with different mental health problems. Accordingly, helping clients think in a more balanced way is a core component of cognitive behavioral therapy (CBT). This information handout describes 20 of the most clinically-relevant cognitive biases: all or nothing thinking, arbitrary inference, catastrophizing, disqualifying the positive, emotional reasoning, externalizing, fortune telling, hindsight bias, jumping to conclusions, labeling, magnification and minimization, mental filter, mind reading, overgeneralization, permissive thinking, personalizing, self-blame, “should” statements, social comparison, and thought-action fusion.