Mind-mindedness (MM) refers to caregivers' proclivity to treat a child as having an active and autonomous mental life. It has been shown to be a powerful predictor of many developmental outcomes and to mitigate the impact of risk conditions. However, longitudinal studies on MM reporting changes over time and individual differences among mothers have been scant and quite inconclusive, mainly due to the investigation of changes between only two time points. The current study analyzes MM's developmental trajectories across four time points (3, 6, 9, and 12 months of infants' age) along with the moderating effects of four variables (maternal sensitivity, age, education, and family income). The sample included healthy mother-infant dyads (N = 93, 46 female infants), belonging to monolingual Italian predominantly middle-class families, with 15% (n = 14) classified as low income (below the relative poverty threshold). The dyads were videotaped during semistructured play interactions and transcripts were coded for appropriate mind-related comments (AMRCs) and nonattuned mind-related comments (NAMRCs). Mothers' AMRCs, compared to NAMRCs, showed more temporal stability. Both AMRCs and NAMRCs showed a linear decrease with individual differences across dyads decreasing over time, and dyads becoming increasingly similar one with the other. Low income moderated the normative trend of appropriate mind-related comments. These findings suggest that MM, while depending largely on an individual trait at earlier ages, when infants' mental states are less intelligible, adapts to the increase of infants' sociocommunicative repertoire over time. They also highlight the importance of ecological constraints on the quality of caregiving. (PsycInfo Database Record (c) 2022 APA, all rights reserved).