The purpose of this study was to determine the effect of inquiry-based agriscience instruction on student scientific reasoning. Scientific reasoning is defined as the use of the scientific method, inductive, and deductive reasoning to develop and test hypothesis. Developing scientific reasoning skills can provide learners with a connection to the scientific process by creating knowledge through evidence-based or authentic investigations. Higher reasoning scores indicate the learners' ability to change a nonscientific belief based on factual evidence. This quasi-experimental study investigated the effect of two teaching methods (inquiry-based instruction and the subject matter approach) on agriscience student scientific reasoning. Fifteen agriscience education classes confined within seven secondary schools across the United States participated in the study. Utilizing univariate analysis of covariance, there was a statistically significant difference between groups based on scientific reasoning. Those students taught through inquiry-based instruction were reported as having higher scientific reasoning than students taught through the subject matter approach. (Contains 1 figure and 4 tables.)