2024 Abstract: Purpose – The prevailing view in the existing literature is that open innovations (OI) increase the innovative performance of enterprises. The author examines whether the same OI practices are equally important for sole entrepreneurs, micro firms, small firms, medium-sized and large enterprises in introducing radical innovations and which set of OI practices is best for a firm, given the firm’s size. Design/methodology/approach – In this study probit models were used on a sample of 915 innovative Serbian enterprises. Findings – OI is important for all enterprises introducing radical innovations. However, not all OI practices are equally effective in each enterprise size group. The set of OI practices leading to radical innovations depends on the firm size. Cooperation with others is not important for sole entrepreneurs and micro and large companies in introducing radical innovations. Still, cooperation’s role is predominant in small and medium-sized enterprises. Also, certain OI practices are important for all enterprises, whilst others do not contribute to radical innovations, regardless of the firm size. Practical implications – Owners/managers can save considerably by avoiding the allocation of resources to OI practices that result in little to no contribution to radical product commercialisation. At the macroeconomic level, these findings can help policymakers create adequate (tailor-made) public policies to achieve innovation in each specific group of firms. Originality/value – This study demonstrates that not all OI practices are equally important for achieving radical production solutions in each group of enterprises info:eu-repo/semantics/article Keywords Open innovation practices, Radical innovation, Firm size Aničić, Zorica European Journal of Innovation Management volume: 27 number: 6 startpage: 1986 endpage: 2014 All rights reserved eng https://phaidrabg.bg.ac.rs/o:35722 doi:10.1108/EJIM-06-2022-0311 ISSN: 1460-1060 application/pdf 427272 bytes The importance of specific open innovation practices for radical innovations within companies of different sizes