Abstract: The present invention relates to compositions and methods for inducing mammary epithelial cell differentiation in mammalian subjects. More specifically, the present invention relates to methods for inducing mammary epithelial cell differentiation which comprise increasing the levels of galanin in the mammary tissue of the subject. In one aspect the present invention relates to a method of increasing milk production in a lactating mammal which comprises increasing the level of galanin or an analog thereof in the mammal. In another aspect the present invention relates to a method of enhancing mammary development in a mammal, the method comprising administering to the mammal galanin or an analog thereof in conjunction with prolactin or an analog thereof. In yet another aspect the present invention relates to a method for inhibiting mammary epithelial tumours by administering an inhibitorially effective therapeutic amount of galanin or an analog thereof.