This study revealed some of the factors that influence preservice elementary teachers' instructional planning in word problem solving by examining preservice teachers' conceptions of how to teach word problem solving. Twenty-one interviews of preservice teachers were conducted before and after the mathematics methods course and the protocols were categorized into a set of constructs elicited from their statements regarding instructional planning and processes by examining similarities, differences, and changes in individual interview statements. Three general conceptions expressed by preservice teachers were instructional strategies, concerns about student ability, and past experiences. While some preservice teachers showed certain conceptual changes in their instructional planning after the methods instruction, others were consistently influenced by other factors such as their prior educational experiences. Many preservice teachers were concerned about students' prerequisite levels in instructional planning and were aware that they were not equipped with the necessary knowledge. Fewer preservice teachers mentioned incorporating their own personal experiences in instructional planning at the end of the methods course. Contains 40 references. (Author/AP)