Plant-based dairy alternative beverage sales have increased in recent years. Plant-based dairy alternatives often advertise on a platform of sustainability and environmental commitment. To successfully position and market dairy products in this competitive environment, dairy companies must understand the consumer definition of and importance placed on sustainability, as well as communicate sustainability information effectively. The objective of this study was to characterize consumer perception of the sustainability of milk and dried dairy ingredients and their respective plant-based alternatives. Focus groups and 2 online surveys were conducted. In the first survey, maximum difference scaling was used to rank the importance of specific dairy product attributes to sustainability, along with an exercise in which respondents selected whether a fluid milk or protein powder product was sustainable. A follow-up survey included 2 exercises in which respondents selected whether generic dairy products or dried dairy ingredients were sustainable, natural, healthy, trustworthy, or ethical. Over half of dairy product consumers reported that they looked for sustainability-related information. Consumers who purchased both plant-based dairy alternative and dairy products placed a higher self-reported importance on sustainability than those who purchased dairy products only. Focus group and survey maximum difference scaling results identified 5 key attributes for sustainability: minimal carbon footprint/greenhouse gas emissions, few/no preservatives, animal happiness and welfare, and simple/minimal ingredients. Plant-based dairy alternatives followed by fluid milk and protein powders were considered more sustainable than dairy products, but package type and organic status also played a role in consumer sustainability perception. Product labels were the most common source of sustainability information, although consumers also sought information on websites affiliated and unaffiliated with dairy companies. There was cognitive overlap among the terms sustainable, natural, healthy, ethical, and trustworthy as they relate to dairy products, but consumers used the terms distinctly. Consumers perceived differences in these terms between general categories of dairy as well as among products in a specific dairy category. Dairy companies may be able to differentiate themselves by helping consumers make these choices by simplifying sustainability-related messaging and by maintaining open, transparent communication regarding sustainability.