Femtocell is envisioned as a highly promising solution for indoor wireless communications. The spectrum allocated to femtocells is traditionally from the same licensed spectrum bands of macrocells. The capacity of femtocell networks is highly limited due to finite number of licensed spectrum bands and the interference with macrocells and other femtocells. A radically new communication paradigm is proposed by incorporating cognitive radio in femtocell networks. The cognitive radio enabled femtocells are able to access spectrum bands not only from macrocells but also from other licensed systems (e.g. TV), provided the interference from femtocells to the existing systems is not harmful.