Folk wisdom suggests that “you cannot teach an old dog new tricks.” Accordingly, as the average age of the workforce increases, there is a potential concern based on negative stereotypes that organizations will become less innovative. Drawing from lifespan development theories and theorizing on innovation, we explore this concern by testing, at the organization level of analysis, whether the average age of employees is indirectly related to climate for innovation through employees’ aggregate focus on opportunities (i.e., a negative indirect effect) and work engagement (i.e., a positive indirect effect). Moreover, we proposed that organizational age diversity is a protective resource that moderates these relationships, such that they are weaker in organizations with high as compared to low age diversity. Organization-level data were collected from teaching and non-teaching staff in n = 133 schools across two time points separated by four years (Time 1 n = 3,712 respondents; Time 2 n = 5,183 respondents). Results suggest that the average age of employees within schools was negatively related to employees’ aggregate focus on opportunities which, in turn, positively predicted climate for innovation above and beyond the positive effect of work engagement. Moreover, the negative indirect effect of average age on climate for innovation through aggregate focus on opportunities was weaker for organizations with high age diversity. Overall, these findings contribute to a better understanding of relationships between age and age-related characteristics and climate for innovation at the organization level, and challenge common misunderstandings regarding the role of age in the workplace.