The best choice of protein source for preserving muscle mass with advancing age is a topic of considerable interest in nutrition for both health and sustainability reasons. Scientists generally agree that the primary driver of muscle loss with advanced age — at least in healthy individuals — is the reduced stimulation of muscle protein synthesis (MPS) in response to anabolic stimuli, such as protein intake and/or physical activity. This phenomenon is termed “anabolic resistance” and presents a public health challenge to “growing older with health and vitality.” The focus of this presentation is on how proteins derived from dairy, meat, and plant sources differ in their capacity to stimulate MPS and therefore preserve muscle mass in older adults.   Animal sources of protein are often touted as more anabolic than plant proteins. This viewpoint is commonly attributed to a greater digestibility and superior essential amino acid and leucine profile of most animal-derived proteins compared with plant-based proteins. Consistent with this notion, studies conducted within a controlled laboratory setting have demonstrated that either beef, milk, or whey protein ingestion stimulates a greater postprandial response of MPS compared with a dose-matched soy or wheat protein source in physically active young and older adults.  However, as a note of caution, the validity of this claim that animal proteins are more anabolic than plant proteins is limited to the comparison to only two plant-based proteins, namely soy and wheat. This presentation challenges this broad viewpoint by highlighting the anabolic potential of alternative plant-based protein sources with application to maintaining the size and quality of ageing muscles.