In recent years, consumer interest in pork raised without or with limited in-feed antibiotics and the introduction of the Veterinary Feed Directive have driven producers to look for alternatives to the use of antibiotic growth promoters (AGPs) in feed. There are numerous products already available that have the potential to be considered as AGP alternatives, although the effectiveness of many of these products has so far not been clearly demonstrated. Current data involving these AGP alternative ingredients are widely variable, and studies evaluating their effects lack consistent methodology and reporting of critical information. This leaves a significant gap in or knowledge about the effectiveness of these products and the ability to make comparisons across studies. In order to most efficiently identify useful AGP alternatives, it is necessary to first increase the consistency with which studies evaluating them are conducted. The objectives of this experiment were: 1) to develop and validate guidelines for studies on alternatives to AGPs to ensure progress in developing and assessing the scientific merit of such projects is as rapid as possible and to facilitate the comparison of research results across multiple studies, and 2) to evaluate the effects of example AGP alternatives in varying pen-group sizes.