In a socially diverse sample of 206 infant–mother pairs, we investigated predictors of infants’ attachment security at 15 months, with a particular emphasis on mothers’ tendency to comment appropriately or in a non-attuned manner on their 8-month-olds’ internal states (so-called mind-mindedness). Multinomial logistic regression analyses showed that higher scores for appropriate mind-related comments and lower scores for non-attuned mind-related comments distinguished secure-group mothers from their counterparts in the insecure-avoidant, insecure-resistant, and insecure-disorganized groups. Higher scores for appropriate mind-related comments and lower scores for non-attuned mind-related comments also independently predicted dichotomous organized/disorganized attachment. General maternal sensitivity predicted neither attachment security nor organization, although sensitivity was found to relate to dichotomous secure/insecure attachment specifically in the context of low socioeconomic status. The findings highlight how appropriate and non-attuned mind-related comments make independent contributions to attachment and suggest that mind-mindedness is best characterized as a multidimensional construct.