PurposeThis paper aims at exploring the factors that are important for the digital development of small and medium-sized enterprises (SMEs) in response to the coronavirus disease 2019 (COVID-19) crisis compared to large-sized enterprises.Design/methodology/approachUsing data from a survey in Greek firms during the pandemic, econometric models are estimated to identify factors that are related to the expansion of digital marketing and e-commerce practices of SMEs and large-sized enterprises based on the technology–organization–environment framework.FindingsThe results suggest that while further investments in information and communication technology (ICT) infrastructure are important for the digital development of SMEs during the COVID-19 crisis, it is the innovative activities that advance the digitalization of large-sized enterprises. Also, SMEs, which implement flexible human resource (HR) practices (such as remote work) and face delays in the supply chain due to the pandemic, appear to have increased probability of expanding their digital marketing and e-commerce. On the contrary, HR practices do not seem to matter for large firms, while new regulations appear to discourage their digital development during the COVID-19 crisis.Originality/valueThis is the first study which empirically explores the digital reactions of SMEs compared to those of large-sized enterprises in a pandemic crisis context. It advances the limited knowledge on the potentially different responses of SMEs and large-sized enterprises to major external shocks with respect to their digital marketing and e-commerce expansion.