Many freshmen entering college are living away from home for the first time and making important lifestyle choices that impact their risk of developing chronic diseases. Purpose: The purpose of this study was to examine the physical activity behavior of college freshman females. Methods: One-hundred thirty seven freshman females (age: 18.2 ± 0.4 years; 84% Caucasian) at a large university in the south central United States completed the International Physical Activity Questionnaire (IPAQ) short form and had their height and weight measured at the beginning and end of their freshman year. The IPAQ assesses vigorous, moderate, and walking activities during the previous 7 days. MET-hours per week were determined by weighting each category of activity with a corresponding MET value according to IPAQ recommendations (vigorous = 8 METs; moderate = 4 METs; walking = 3.3 METs). Height and weight were used to compute body mass index (BMI: kg/m2). Descriptive statistics, dependent t-tests, and Wilcoxon matched-pairs signed-rank tests were calculated. Results: Most participants were meeting national recommendations for moderate and/or vigorous physical activity at both time points (Fall: 98%, Spring: 93%). BMI increased significantly (Fall: 21.9 ± 2.5 kg/m2, Spring: 22.4 ± 2.5 kg/m2, p < .05) and walking decreased significantly [Fall: median (interquartile range) = 19.8 (20.9) MET-hours per week, Spring: median (interquartile range) = 12.4 (23.1) MET-hours per week, p < .05] during the academic year. However, participation in vigorous, moderate, and total activity did not change significantly (p > .05). Conclusions: This sample of highly active freshman females decreased their weekly walking activity during their first year at the university. This reduction is equivalent to decreasing energy expenditure by approximately 433 kcal per week [mean body weight at baseline (58.5 kg) * MET-hour per week decrease (7.4 MET-hours per week)], which could result in weight gain of 3.7 pounds per academic year if dietary intake and participation in other physical activities remained stable. Keyword(s): exercise/fitness/physical activity, health promotion