The digital age offers unprecedented opportunities for firms to access new knowledge for innovation. Both academics and managers have identified crowdsourcing (CS) as one relevant way to do so. CS for innovation involves outsourcing problem-solving or creative tasks to the crowd. To benefit from CS, absorptive capacity (ACAP) is critical; this can be enhanced by prior knowledge and past experience with a partner. However, in the CS con-text, firms open themselves up to undefined, anonymous partners through the Internet, hence the development of ACAP becomes more difficult. The literature on ACAP describes how internal integration mechanisms encourage the absorption of knowledge but fails to clearly address the way in which uncommon knowledge is integrated. Although literature has acknowledged the beneficial role of a wider spectrum of influential internal and external mechanisms on uncommon knowledge, few empirical studies have addressed the distinctive effect of these mechanisms on the absorption of anonymous partners’ knowledge. To fill this gap, this study identifies relevant integration mechanisms and how they impact upon different ACAP dimensions in the CS context. Five case studies reveal the distinctive influence of integration mechanisms depending on the nature of the CS activity. Our results extend research on ACAP in the little studied digital open context, investigating the absorption of uncommon knowledge from unidentified partners. From a managerial perspective, this study shows that managers need to pay attention to integration mechanisms in order to support the absorption of knowledge from the crowd. More precisely, our study suggests that the main focus should not be on external mechanisms, but also on internal mechanisms. Finally, we open up a new theoretical debate on how these mechanisms should be combined.