The experience of prostate cancer is for most men a major life stress with the psychological burden of this disease falling more heavily on those who are younger. Despite this, being young as it applies to prostate cancer is not yet clearly defined with varied chronological approaches applied. However, men's responses to health crises are closely bound to life course and masculinities from which social roles emerge. This paper applied qualitative methodology (structured focus groups and semistructured interviews with expert informants) using interpretative phenomenological analysis to define what it means to be young and have prostate cancer. Structured focus groups were held with 26 consumer advisors (men diagnosed with prostate cancer who provide support to other men with prostate cancer or raise community awareness) and health professionals. As well, 15 men diagnosed with prostate cancer and in their 40s, 50s, or 60s participated in semi-structured interviews. Participants discussed the attributes that describe a young man with prostate cancer and the experience of being young and diagnosed with prostate cancer. Chronological definitions of a young man were absent or inconsistent. Masculine constructions of what it means to be a young man and life course characteristics appear more relevant to defining young as it applies to prostate cancer compared with chronological age. These findings have implications for better understanding the morbidities associated with this illness, and in designing interventions that are oriented to life course and helping young men reconstruct their identities after prostate cancer.