A group of 34 subjects each with a reading deficiency of 1 year or more were studied on the following variables: visual perception, arithmetic, memory, auditory perception, and laterality. The age range was from 8 to 13 years, with a mean grade deficiency of 1.93 years. Using the Minnesota Percepto-Diagnostic test as the diagnostic instrument, the subjects were assigned to one of three reading categories: primary retardation, secondary retardation, or retardation due to brain injury. The study was divided into two problems. The first compared the three reading categories on each variable by analysis of variance and by t tests. Auditory recall and consistency of direction in drawn figure placement were associated with brain injury. The second problem compared the three reading categories with normative populations on each of the variables by means of t tests. The primary group was not significantly different from the normative populations on any of the variables. Difficulty with arithmetic was found to be associated with secondary reading retardation, and poor auditory recall was associated with brain injury. A continuum of organicity underlying all three diagnostic categories was suggested. References are included. (Author/WB)