This paper develops a Banking Stability Indicator (IEB) for the Peruvian banking system. This indicator intends to contribute to the construction of an operational measure of "financial stability". Thus, authorities may have an additional tool for the design of policies aimed at preserving financial stability. The IEB is measured from each banks' balance sheets, then aggregated to get the IEB for the whole system. The results are consistent with observations: the banking system IEB recorded a stable evolution similar to the banking system response during the international financial crisis 2007 – 2009.