Background and Aim: Relative contribution of different domains on walking speed is largely unknown. This study investigated what are the central factors associated with maximal walking speed among older people. Methods: Cross-sectional analyses of baseline data from the SCAMOB study (ISRCTN 07330512) involving 605 community-living ambulatory adults aged 75-81 years. Maximal walking speed, leg extensor power, standing balance and body mass index were measured at the research center. Physical activity, smoking, use of alcohol, chronic diseases and depressive symptoms were self-reported using standard questionnaires. Results: The mean maximal walking speed was 1.4 m/s (range 0.3-2.9). In linear regression analysis, age, gender and body mass index explained 11% of the variation in maximal walking speed. Adding leg extensor power and standing balance into the model increased the variation explained to 38%. Further adjusting for physical activity, smoking status and use of alcohol increased the variation explained by additional 7%. A minor further increase in variability explained was gained by adding chronic diseases and depressive symptoms in the model. In the final model, the single most important factors associated with walking speed were leg extensor power, standing balance and physical activity and these associations were similar in men and women and in different body mass index categories. Conclusions: Lower extremity impairments and physical inactivity were the central factors associated with slow walking speed among older people, probably because these factors capture the influences of health changes and other life-style factors potentially leading to walking limitations.