The aim of this research is to describe the process of pattern generalization based on the taxonomy for categorizing generalization i.e. relating, searching and extending. The subjects were the fifth and the sixth grade students of elementary school. Qualitative data were obtained from their written work when they solved the problems of patterns and from interviews. First, at the first stage, students were asked to solve a problem of pattern generalization and at the second stage, they were interviewed in order to find out whether they understood the process of generalization or not. The results showed that the students focused on two aspects when they were facing the problem of pattern generalization, that is, they focused on the number of squares in the figure without considering the shape of the figure and they focused on the shape of the figure by paying attention to the square in the middle and to the addition of square on each side of the figure. The result of this study also revealed that students who focused on the shape of the figure found it more easily to formulate its general rule.