This study investigated the relationships among company average age, company work ability, and company performance by examining (a) the effects of employee average use of selection, optimization, and compensation (SOC) personal strategies and high-involvement work practices (HIWPs) on employee work ability; (b) the buffering effects of both employee average use of SOC and HIWPs on the negative relationship between company-level average age of employees and employee work ability; and (c) the link between company average age and company performance as mediated by company work ability. Analysis was conducted on data from 70 Finnish companies in the retail and metal industries and their 889 employees. Results showed that company average age was negatively related to company work ability, which in turn was positively related to company performance assessed by company managers. HIWPs were positively related to company work ability. Employee average use of SOC strategies buffered the negative effect of company average age on company work ability. Theoretical and practical implications of these findings are discussed.