To identify the characteristics and risk factors of malnourished children age ≤24 months. A case-control study was conducted at two clinics in Cartagena, Colombia. WHO reference populations for weight-for-height and height-for-age Z-scores were utilized to determine acute and chronic malnutrition. Cases are children with mild, moderate, or severe malnutrition, determined by a Z-score < -1SD; controls are children with Z-scores between -1SD and +2SD. Cases were recruited between August 2014 and October 2015. Chart review and in-person questionnaires were used to gather information on the child’s age, height, weight, birth weight and gestational age, maternal characteristics, socioeconomic factors, and household characteristics. Odds Ratios with 95% CI were estimated. Of the total 481 children recruited, 71% had malnutrition, 53% are male and have a median age of 10.93 (SD± 6.57) months, 86% pertain to socioeconomic stratum 1 (families earning minimum wage or less), and 96% are covered by public health insurance. 139 cases were randomly matched to 139 controls according to gender and age. Childhood malnutrition was significantly associated with low birth weight (OR 7.75; 2.74 – 21.95), preterm birth (OR 2.31; 1.29 – 4.16), maternal malnutrition (OR 3.00, 1.09 – 8.25), and adolescent motherhood (OR 2.25; 1.14 – 4.44). Breastfeeding was a protective factor, with any exposure to breastfeeding (OR 0.33; 0.11 – 1.03), breastfeeding duration >6 months (OR 0.17; 0.05 – 0.61), any exposure to exclusive breastfeeding (OR 0.52; 0.31 – 0.88), and duration of exclusive breastfeeding >6 months (OR 0.40; 0.16 – 0.99). Significant protective maternal characteristics include presence a partner (OR 0.40, 0.22 – 0.74) and completion of secondary education (OR 0.61, 0.36 – 1.02). Prevention of adolescent pregnancy and the improvement of prenatal care should be targeted in order to prevent infant malnutrition. Additionally, breastfeeding for ≥6 months should be promoted to improve infant nutritional status