The paper summarises theoretical and conceptual issues related to two central phenomena in today's economy. The first is the so-called "External Constraint on Economic Growth" or "Balance of Payments Constraint". The second phenomenon is that of international capital movements ("Financial Flows"), one expression of which is "Capital Flight". These cross-border flows have grown very significantly since the beginning of the 21st century. These two issues are the subject of extensive theoretical and empirical analysis, and constitute structural problems of Argentina's economy. In these pages we seek to describe, distinguish and analyse theoretically and empirically the relationship between both phenomena: External Restriction and Capital Flight.