This study evaluated “Every Step Counts!”—a 10-wk, structured walking intervention in a community-based senior organization—on promoting physical activity participation, fitness, and well-being among older adults (age ≥ 55 yr). The intervention prescribed pedometer-defined walks in weekly walking schedules. These were fitness-tailored and structured in walking load (intensity/volume) according to the principles of training progression. This intervention was offered as a social activity at meeting points of a community-based senior organization. Twenty-nine meeting points (n = 432) constituted the intervention condition. Ten meeting points (n = 148) formed the wait-list control condition. Measurements were organized at intervention start (pretest) and end (posttest). Intention-to-treat linear mixed models showed small positive intervention effects on physical activity, fitness, and aspects of well-being. These results confirm the effectiveness of structured walking interventions with systematic training progression and underscore the value of community-based senior organizations as intervention settings for older adults.