Extended shelf life (ESL) fluid milk products have made significant gains in sales across the world. Research by the National Center for Biotechnology Information indicates that psychrotolerant spore-forming bacteria (PSF) often lead to premature spoilage in these beverages. PSF may reduce pasteurized milk shelf life by several days, thus restricting a processor’s ability to market the milk as ESL. Studies have shown that almost 20% of the most commonly sold HTST pasteurized milk in the United States is discarded before consumption. Much of this microbial spoilage can be attributed to PSF. Extensive studies have shown that the Paenibacillus strains are the predominant PSF found in fluid milk and can originate on the farm environment from sources such as fermented feeds and bedding. Additionally, udder cleanliness and milking preparation directly correlate with raw milk quality in the bulk tank. These highly heat-resistant endospores exhibit thermophilic and mesophilic properties that allow them to survive harsh environments such as UHT pasteurization. Post pasteurization contamination (PPC) has also been implicated in PSF growth. Biofilm formation in corners, cracks, crevices, and dead ends of stainless steel processing lines can result in PPC because milk is an ideal culture medium for the growth of food spoilage flora such as PSF. Effective practices to extend shelf life of milk by limiting PPC and PSF include using aseptic lines that eliminate corners, strict adherence to cleaning-in place processes (CIP), and biofilm control by detergents. Controlling PSF in the milk supply offers dairy producers and processors the opportunity to improve milk quality and profitability.