We examined the association between maternal mental health symptomatology, sensitivity, and toddlers’ attachment security in a low-SES Turkish sample. Mothers (N= 148) and their 12- to 38-month-old toddlers (Mage = 23.18 months) from economically impoverished backgrounds were recruited. Home visits involved naturalistic home observations of mother–toddler interactions and filling out questionnaires including Brief Symptom Inventory. Trained coders independently assessed video-recorded mother-toddler interactions for maternal sensitivity and toddlers’ attachment security using the Maternal Behavior Q-Sort and with Attachment Q-Sort, respectively. Maternal symptoms were negatively associated while maternal sensitivity was positively associated with attachment security. Further, this relationship remained significant even after controlling for SES. However, maternal sensitivity did not significantly mediate the link between maternal symptoms and toddlers’ attachment security. We showed that the importance SES and maternal factors on attachment security in a disadvantaged group, which would facilitate developing preventive interventions specifically addressing maternal mental health and high-risk groups.