Purpose: Drawing on expectancy theory, this research explores how and when volunteers' motivational drives for volunteering relate to organizational policies and practices. The paper analyses four areas of motivational association -- affiliation, beliefs, career development and egoistic motives -- together with organizational human resource (HR) policies and practices. Design/methodology/approach: The study used a qualitative approach and through 17 interviews of the volunteer managers associated with 13 non-profit organizations (NPOs) examined that how through HR policies and practices, an NPO efficiently taps motivational drives of volunteers and maintains their spirit of volunteering. Findings: The findings of the study indicated that the same behaviour may serve different functions for different individuals. Most of the motivational drives need to be tapped with specific tasks and events to become a source of fulfilment for volunteers, this plays a vital role in their decisions to continue volunteering. NPOs' HR practices without volunteers' motivation cannot serve any purpose. In the same vein, volunteers' motivation cannot sustain for a longer period if it is not properly linked with organizational HR practices. Research limitations/implications: The research findings may lack generalizability because of the selected research approach. Originality/value: A great part of existing research, not previously captured in literature, is focussed on the assessment of the motivational underpinnings with respect to HR policies and practices.