For tetrapods that use parasagittal limb posture, many studies have shown that locomotor patterns change as body size increases. However, little is known about such changes for animals using non-parasagittal limb posture. Crocodylians are the largest living quadrupeds with non-parasagittal limb posture, thus, they provide an opportunity to study how non-parasagittal locomotion changes as size increases. To test for such changes, we used six juvenile American alligators (small: n = 3, 0.23–0.25 kg; large: n = 3, 1.40–2.05 kg) to characterize normalized stride parameters, joint angles, single-limb forces, and joint moments as they walked across a force platform. Large juveniles walked slower and with shorter steps. Normalized peak vertical forces were similar in fore- and hindlimbs of small juveniles, but hindlimbs showed greater vertical forces than forelimbs in large juveniles. In addition, the two size classes used similar forelimb kinematics, but the hindlimbs showed more erect joint angles in large juveniles than in small ones. These differences in kinematics and locomotor forces may relate to a posterior shift in the center of mass (CoM) between small and large juveniles. They also may have consequences for skeletal loading, as the larger forelimb vertical forces and more abducted hip of small juveniles produce greater normalized moments for shoulder adduction, elbow flexion, and wrist flexion in the forelimbs, and hip adduction in the hindlimbs. Previous studies suggested that upright locomotion led to higher bone strains among large juveniles. This makes their ontogenetic shift to more upright posture puzzling, and calls for comparisons of limb bone loads between small and large alligators.