The central argument of this chapter is that there are multiple and complex explanations as to why people decide to volunteer or not volunteer, and why they choose a specific volunteering domain and role. Volunteers are often not consciously aware of some of their motives for taking part in volunteering. An individual’s choice as to whether to volunteer, and how to volunteer, is founded on a complex range of different influences, triggers, desires and needs, that may affect them throughout their lives, and are contingent on that individual’s personal circumstances, skills, values, identity and personality, and changes therein, over their lifecourse. The chapter draws on survey data on the motives and benefits people attributed to volunteering during the timeframe of the study; however, it relies on the accounts of Mass Observation Project writers to more fully explore these issues. It examines influences such as parental role-modelling and guidance; childhood volunteering; value systems; being asked; the need for therapeutic activities, leisure, and career advancement; and the need to belong. It also considers some of the negative influences and triggers that can result in would-be volunteers refusing to take part, feelings of coercion, and people becoming disillusioned in their volunteering.