The spectrum of breast disease in children differs from that in adults, and approach is usually conservative as breast malignancy in adolescents is very rare. Knowledge of normal physiological breast development is essential to distinguish from pathologies, and thus clinical examination is the most important step followed by ultrasound as the modality of choice. The purpose of this chapter is to elucidate imaging features of normal breast development, benign and rare malignant neoplasms, and metastatic conditions as a guidance for appropriate management options. On the other hand, there is a wide spectrum of benign and malignant masses seen during pregnancy and lactation. The physiological changes that occur in the breast parenchyma during pregnancy and lactation are due to hormonal influences. This causes changes in the breast parenchyma and makes clinical examination and radiological imaging very challenging. It is important to have a good knowledge of the physiological changes that occur during this phase. A vast majority of the masses that are seen during pregnancy and lactation are benign; however, the possibility of pregnancy-associated breast cancer should be kept in mind as these cancers are detected late and are biologically aggressive. This chapter will include the common pathologies that are seen during pregnancy and lactation and their imaging features.