PURPOSE: Finding a breast mass in a child provokes apprehension in parents, especially in those with a family history of breast cancer. Clinicians must decide between serial imaging or biopsy of the mass. Herein, we identify management differences in those with and without a positive family history, as well as identify cost differences. METHODS: An institutional retrospective review was performed of patients (2-18 years of age) with a diagnosis of breast mass. Patient demographics, presentation, medical and surgical history, physical exam, imaging, and pathologic diagnosis were collected. Cost data were acquired from the pediatric health information system (PHIS). Costs were compared between patients managed by biopsy versus serial ultrasounds. Bivariate analyses including Pearson's Chi-square, student's t tests, and logistic regression were performed. RESULTS: The probability of biopsy increases with age (p = 0.0001) and female gender (p = 0.006). Biopsy rate is higher for larger masses (p < 0.0001), growing size (p < 0.0001), and in patients with a positive family history of breast cancer (p < 0.0001). The average cost of care for management with initial excisional biopsy was $4491 versus those with serial ultrasounds ($986) (p < 0.0001). CONCLUSIONS: In patients with small lesions, even with a family history of breast cancer, non-operative monitoring is a safe and cost-effective alternative to invasive biopsy.