This paper aims to find indicators that can be used to monitor Indonesia's external vulnerability as well as an early warning system of crisis. The study is conducted by evaluating a number of indicators deployed in the previous studies by using signaling method. An analysis of external vulnerability is facilitated by separating the pressure of vulnerabilities into four zones, namely normal, alert, cautious, and suspected crisis. The study obtains 12 external indicators that are then aggregated to produce a composite index of external vulnerability. The selected indicators and the composite index are well able to capture the external vulnerability.