The foremost index of caregiving quality is child attachment, as supported by attachment theory. Research supports the relevance of early parenting interventions in improving child outcomes in attachment quality to promote public health because of their long-term effects on mental health and functioning. This study aimed at evaluating the impact on both parenting and child outcomes of the Parent-Child Psychological Support Programme® (PCPS), a community-based program individually tailored to parents and their infants during periodic center-based visits to promote attachment security. The evaluation involved two cohorts from "vulnerable populations" and used the resources embedded in the program design without interfering with the normal functioning of the service. From an evaluative research approach, the effects on mothers and children were assessed using a quantitative approach. Pre- and post-test measures (parenting questionnaires) and child attachment quality assessments through the Strange Situation Procedure were examined. The equivalence of the cohorts was verified and used as a baseline for parenting outcomes. PCPS participants demonstrated increased parental competence and self-efficacy, as well as reduced levels of parenting stress. Analysis of the two cohorts showed a significant difference in the number of visits and proxies for intervention, which were associated with the expected pre-post changes in parenting dimensions. The proportion of securely attached children was significantly higher in the "medium-high intervention" group than in the "no/low intervention" group (72.7% vs 54.5%). Furthermore, compared with international baselines, this proportion showed no differences in the "no-/low-intervention" group but demonstrated expected significant differences in the "medium-high intervention" group.