The purpose of this exploratory qualitative study was to determine the reasoning processes used by paramedics to solve clinical problems. Existing research documents concern over the accuracy of paramedics' clinical decision-making, but no research was found that examines the cognitive processes by which paramedics make either faulty or accurate clinical decisions. This study used verbal protocol analysis to examine data obtained by participants' thinking out loud as they concurrently solved and retrospectively reviewed two vignettes of clinical problems. Twenty concurrent verbal protocols and 20 retrospective debriefings were obtained from 10 paramedics purposively recruited for the study. Initial coding proceeded from a model of what was presumed to be true of paramedics' clinical reasoning processes, based on the information-processing theory of problem-solving, prescribed information in the Paramedic National Standard Curriculum, and literature on emergency medicine physicians' problem-solving processes. Codes were revised during data analysis to reflect themes that emerged from the data. Analysis revealed that participants' patient assessment and illness scripts related to the two vignettes were inadequately developed, disorganized, and, in some ways, faulty. Problem identification proceeded primarily by pattern recognition without adequate hypothesis testing. In the absence of adequate illness scripts for pattern recognition and the absence of adequate hypothesis testing, participants generated pseudo-information and used cognitive biases in problem solving. Participants had a low threshold for initiating treatment, often leading to inappropriate treatment being given. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]