This article reviews the mechanisms underlying attentional biases towards threat in anxiety disorders. Attentional biases refer to differential attentional allocation towards threatening compared to neutral stimuli. Research shows that anxious individuals display such biases, while non-anxious individuals do not. The mechanisms of these biases are not well understood, but several models have been proposed to explain them. Attentional biases can be broken down into three components: facilitated attention (faster detection of threatening stimuli), difficulty in disengagement (difficulty shifting attention away from threatening stimuli), and attentional avoidance (avoiding locations where threatening stimuli are presented). These components are mediated by different neural mechanisms. Facilitated attention is likely mediated by the amygdala, which is involved in automatic threat detection. Difficulty in disengagement is likely mediated by attentional control, which is related to the prefrontal cortex. Attentional avoidance is likely mediated by emotion regulation goals, which are also related to the prefrontal cortex. The stages of information processing during which these biases occur are also important. Automatic processing occurs without intent or awareness, while strategic processing is intentional and requires awareness. Threat detection is likely an automatic process, while attentional avoidance is a strategic process. Difficulty in disengagement may involve both automatic and strategic processing. Several theoretical models have been proposed to explain these mechanisms. The cognitive-motivational model suggests that attention to threat is a normal and adaptive mechanism. The cognitive model suggests that attentional bias is related to self-knowledge and voluntary goals. The attentional control theory suggests that anxiety disrupts two central executive functions related to attentional control: inhibition and shifting. The article concludes that there is little theoretical agreement on the components of attentional biases, the mechanisms that mediate them, and the stages of processing during which they occur. However, it is generally agreed that a threat detection mechanism operates at the automatic stage of processing and underlies facilitated attention to threat. The lack of agreement makes it difficult to understand why attention is biased towards threat in anxious individuals.This article reviews the mechanisms underlying attentional biases towards threat in anxiety disorders. Attentional biases refer to differential attentional allocation towards threatening compared to neutral stimuli. Research shows that anxious individuals display such biases, while non-anxious individuals do not. The mechanisms of these biases are not well understood, but several models have been proposed to explain them. Attentional biases can be broken down into three components: facilitated attention (faster detection of threatening stimuli), difficulty in disengagement (difficulty shifting attention away from threatening stimuli), and attentional avoidance (avoiding locations where threatening stimuli are presented). These components are mediated by different neural mechanisms. Facilitated attention is likely mediated by the amygdala, which is involved in automatic threat detection. Difficulty in disengagement is likely mediated by attentional control, which is related to the prefrontal cortex. Attentional avoidance is likely mediated by emotion regulation goals, which are also related to the prefrontal cortex. The stages of information processing during which these biases occur are also important. Automatic processing occurs without intent or awareness, while strategic processing is intentional and requires awareness. Threat detection is likely an automatic process, while attentional avoidance is a strategic process. Difficulty in disengagement may involve both automatic and strategic processing. Several theoretical models have been proposed to explain these mechanisms. The cognitive-motivational model suggests that attention to threat is a normal and adaptive mechanism. The cognitive model suggests that attentional bias is related to self-knowledge and voluntary goals. The attentional control theory suggests that anxiety disrupts two central executive functions related to attentional control: inhibition and shifting. The article concludes that there is little theoretical agreement on the components of attentional biases, the mechanisms that mediate them, and the stages of processing during which they occur. However, it is generally agreed that a threat detection mechanism operates at the automatic stage of processing and underlies facilitated attention to threat. The lack of agreement makes it difficult to understand why attention is biased towards threat in anxious individuals.