This chapter outlines a number of factors that have impacted the research into instructional animations. It describes how the findings from comparisons between animations and statics, the major research paradigm, has found mixed results showing that animations are not always more effective than equivalent static pictures. We also describe some mounting evidence that animations seem to be particularly more suited to learning human motor skills rather than other types of knowledge and skills. However, we conclude that it is difficult to have total confidence in the research because many studies have inbuilt design biases that have not been controlled for. In addition, three learner characteristics (spatial ability, gender, and prior knowledge), which have been shown to influence the effectiveness animations, are also often ignored in the research. We discuss the transient nature of information present in animations that increases cognitive load and is a major impediment to learning. We also outline a number of compensatory strategies, such as learner interactivity and segmentation, that can support learning from animations, and describe how more general learning strategies, such as gesturing and collaboration, can be used in tandem with animations to facilitate greater learning.