The purposes of this study were to determine the effects of Minicourse 18 on the development of 27 specific teacher behaviors related to teaching reading decoding skills by a group of inservice and preservice teachers of primary grade children, and to determine the effects of the teacher training upon pupil performance in reading. Minicourse 18 was designed by the Far West Laboratory for Educational Research and Development to improve teacher effectiveness in aiding children in their acquisition of reading decoding skills. Fourteen inservice teachers and nineteen preservice teachers served as subjects. Seven inservice teachers and nine preservice teachers were trained with Minicourse 18, and the remaining seventeen subjects served as a control group. All of the subjects taught a twenty- to thirty-minute lesson on reading decoding skills to three pupils one week before and two weeks after the training of treatment panel teachers. Some of the findings indicated that training with Minicourse 18 contributed significantly to the development and refinement of behaviors related to teaching reading decoding skills. Also, training with Minicourse 18 appeared to have provided teachers with a more systematic approach to teaching reading decoding skills. (WR)