Teacher knowledge is a critical focus of educational research in light of the potential impact of teacher knowledge on student learning. The dearth of research exploring entry-level preservice teachers' geometric knowledge poses an onerous challenge for mathematics educators in initial teacher education (ITE) when designing experiences that develop preservice teachers' geometric knowledge to support the task of teaching. This study examines the geometric thinking levels of entry-level Irish preservice primary teachers (N = 381). Participants' geometric thinking levels were determined through a multiple-choice geometry test (van Hiele Geometry Test) prior to commencing a Geometry course within their ITE program. The findings reveal limited geometric thinking among half of the cohort and question the extent to which pre-tertiary experiences develop appropriate foundations to facilitate a smooth transition into ITE mathematics programs. The study also examines the nature of misconceptions among those with limited geometric thinking and presents suggestions to enhance the geometric understandings of preservice teachers.