With the growing emphasis on the development of scientific inquiry skills, the display and interpretation of data are becoming increasingly important. Graph interpretation competence is, in fact, essential to understanding today's world and to be scientifically literate. However, graph interpretation is a complex and challenging activity. Graph interpretation competence is affected by many factors, including aspects of graph characteristics, the content of the graph and viewers' prior knowledge. For instance, the prior theory and expectations that students have may lead to biases and misinterpretation of graphs. One basic controversy that remains unanswered, for example, is what should we teach first in order to make students scientific literate, how to graph or how to interpret a graph? If it is the case that the ability to interpret a graph be developed prior to the ability to create, then it is important to understand what graph interpretation entails. This paper reviews current literature on graph interpretation competence and argues that it should be explicitly taught given its importance and its complexity. (Contains 2 figures and 5 notes.)