AbstractGeometry serves both as an essential instructional tool in mathematics and a visualizing medium for regulating theoretical and real world constructs. Every mathematics teacher must be adequately equipped with the ways of understanding and thinking of the subject matter required to teach geometry. Relevantly, development of the underlying geometrical reasoning is often subject to the overarching concept of two-dimensional geometric shapes. The purpose of this study is to examine the first-year pre-service undergraduates_ reasoning ability about triangles and quadrilaterals. 140 second-semester undergraduates in lecture setting were given a standardized geometry test, namely the van Hiele Geometric Test (VHGT) which contains 20 multiple-choice questions. A descriptive analysis of the dichotomous data was conducted using SPSS and Winstep programs. The findings suggested that among those pre-service teachers, (a) at least 7.1% performed under the basic, visualization level, (b) at most 5.0.....