Femtocells are low-cost, miniature base-stations intended to improve indoor coverage in 3G networks and beyond. One of the main issues in adopting femtocells en masse is the surge in interference to the mobile users served by the macrocell arising from unplanned networks and private access. Therefore, distributed power control mechanisms for femtocells are essential to shield the existing users of the macrocell as well as to enable scalable femtocell deployments. This paper studies several such power control schemes that strike an effective balance between the throughput of the femto users and the degradation in macrocell performance.