Infants show very early sensitivity to a variety of behavioral cues (such as self-propulsion, equifinal movement, free variability, and situational adjustment of behavior) that can be exploited when identifying, predicting, and interpreting goal-directed actions of intentional agents. We compare and contrast recent alternative models concerning the role that different types of behavioral cues play in human infants' early understanding of animacy, agency, and intentional action. We present new experimental evidence from violation of expectation studies to evaluate these alternative models on the nature of early development of understanding goal-directedness by human infants. Our results support the view that, while infants initially do not restrict goal attribution to behaviors of agents exhibiting self-propelled motion, they quickly develop such expectations.