Research summary: This paper investigates the relationship between hiring and the ability of organizations to evolve their capabilities as they age. While prior research establishes that organizations become rigid to change as they age, it underemphasizes measures that they may take to renew their adaptive potential. I address this gap by investigating whether hiring stimulates change to the knowledge organizations possess. Learning by hiring, I argue, helps organizations to evolve their knowledge as they age by disrupting routine, introducing distant knowledge, and facilitating socialization. I test the effectiveness of these mechanisms using 38 years (1970–2007) of data from the U.S. biotechnology industry, and find that hiring stimulates more change as organizations age, enabling them to renew their knowledge and counter the effects of obsolescence. Managerial summary: As organizations age, they become less responsive to the needs of their environment, resulting in a trend for them to become technologically obsolete. Little is known as to how they may reverse this trend and counter obsolescence. I provide evidence that hiring may be used to stimulate change to organizational knowledge and capabilities as they age by disrupting routine activity, introducing new‐to‐the‐firm knowledge, and inducing incumbent members to learn. Copyright © 2015 John Wiley & Sons, Ltd.