Many individuals aged 65 plus remain in good health and devote their time to various activities after having retired from formal working life. Previous research revealed that appreciation and recognition, contact to others, and knowledge transfer to the younger generation are important reasons for the engagement in post-retirement activities (AARP, 2007; Deller & Maxin, 2009). This paper presents results from a quantitative survey based on these findings. The study explores the motivation of German retirees working on a voluntary basis with Senior Expert Service (N=114). The motivational dispositions appreciation, contact (Grosse Holtforth & Grawe, 2000) and generativity (McAdams & De St. Aubin, 1992), as well as their thematically corresponding job characteristics (e.g., Hackman & Oldham, 1980) are examined in order to identify their relationship to life satisfaction (Diener, Suh & Oishi, 1997) and job satisfaction (Hackman & Oldham, 1980). The sample consisted of senior experts with a mean age of 68 years (M=68.24; SD=3.54), who had spent on average 7 years in retirement. Hierarchical regression analyses show that the generativity motive (desire to pass on knowledge and skills to the younger generation/to society) serves as strongest predictor for both job satisfaction (R=.40; Beta=.31) and life satisfaction (R=.34; Beta=.26). Whereas the analysis of the thematically corresponding job characteristics reveals that the perceived appreciation in relation to the occupation in retirement is the strongest predictor for both job satisfaction (R=.40; Beta=.31) and life satisfaction (R=.33; Beta=27). The results have important scientific and practical implications as they shed light on the motivational patterns, beyond financial needs, of highly-qualified active retirees. This paper promotes the knowledge in retirement research as it helps to understand the particular motivation for post-retirement work. Also, it encourages further research in the field of work motivation for the increasing group of working retirees. International comparison of results is desirable. Practically, the findings can contribute to a better understanding of the basis for a relevant workplace design which is adapted to the needs of workers in retirement. This will contribute to the enhancement of satisfaction, well-being and work motivation of a group feeling healthy and motivated to contribute. The specific conditions that organizations will have to provide to meet the demands of so-called Silver Workers if they want to profit from their experience are discussed.