Attachment theory provides a framework for understanding the correlations among interpersonal relationships, stress, and health. Moreover, adult attachment is an important predictor of mental health. However, there is a lack of systematic reviews that simultaneously examine the associations between adult attachment and both positive and negative indicators of mental health. Consequently, we meta-analyzed 224 studies examining the associations between adult attachment and mental health, using robust variance estimation with random effects. The results (k = 245 samples, N = 79,722) showed that higher levels of attachment anxiety and avoidance were positively correlated with negative affect (e.g., depression, anxiety, loneliness) and they were negatively correlated with positive affect (e.g., life satisfaction, self-esteem). More specifically, there were moderate associations between attachment avoidance and negative mental health (r = .28) and positive mental health (r = -.24). Likewise, there were moderate associations between attachment anxiety and negative mental health (r = .42) and positive mental health (r = -.29). Furthermore, the association between the attachment dimensions and mental health outcomes was also moderated by several variables (e.g., gender, age). Finally, these associations remained statistically significant even when the attachment dimensions were mutually controlled using meta-analytic structural equation modeling. Overall, attachment anxiety had larger associations with mental health than did attachment avoidance. Thus, the current results support robust links between adult attachment and mental health. This may have implications for future research and mental health treatments. (PsycInfo Database Record (c) 2022 APA, all rights reserved).