Adolescent mothers have lower rates of initiation, continuation, and exclusivity of breastfeeding, and even more so in the first pregnancy. Current interventions target adult women, and little evidence is available for breastfeeding promotion among adolescents. This is a pilot study protocol with a parallel, single-blind, randomized, controlled trial design, to evaluate the effectiveness of the intervention “Lactation Counseling” in first-time adolescent mothers to maintain exclusive breastfeeding in the first six months of life. The control group will receive routine education in prenatal care and prenatal and childbirth classes and, the experimental group will receive additionally the intervention “Lactation Counseling”, for four weeks, both conducted by trained nurses. The primary outcome will be the exclusive breastfeeding rate; and the secondary, the breastfeeding knowledge. Measurements will be taken at baseline, post-intervention, and two, four and six months after childbirth. This study will allow the evaluation of the feasibility of an intervention in low-income, Latin American population adolescents.