A study of third party intervention is in fact a study of state behavior. A study of state behavior is meant to examine the roles and influences of this type of international actor. This thesis is centered on a very precise type of state, the third party intervener. It examines the postures and perceptions of these states when they are confronted with a regionally or internationally based dyadic conflict. It supposes that these postures are the result of an interaction effect between the certainty, vulnerability and opportunity variables and utilizes contemporary case studies as empirical evidence of this interaction. It discusses state behavior by investigating the rationale behind alliance formations, conflict contagion and neutrality.