Nurses are assigned a key role in pandemic response, with work engagement considered to be pivotal. The job demands-resources theory assumes that work engagement depends on job resources and job demands. Key job resources and demands have already been proposed for nurses. However, there is no evidence on their importance under pandemic conditions. Hence, the aim of this study was to investigate their relevance to nurses' work engagement during the second wave of the COVID-19 pandemic. The study was carried out in a cross-sectional design and addressed nurses in direct health care settings in Germany. Data was collected administering a quantitative online survey using valid and reliable measures during the second wave of the pandemic. A convenience sample was obtained, including the use of social media, randomly selected health care facilities, and all universities with nursing-related programs in Germany. The dataset for analyses comprised a total of 1,027 cases. The sample included nurses of various educational levels and from different sectors. Multiple linear regression analysis after multiple imputation was used to examine the relevance of key resources and demands for work engagement. Key resources and demands explained 36% of the variance in nurses' work engagement during the COVID-19 pandemic. Positive associations were found between the key resources of autonomy (β¯ =0.072, 95% CI 0.011; 0.133), professional resources (β¯ =0.204, 95% CI 0.124; 0.285), and interpersonal relationships (β¯ =0.178, 95% CI 0.117; 0.240) and nurses' work engagement. On the demands side, lack of formal rewards negatively (β¯ =-0.312, 95% CI -0.380; -0.245) affected work engagement, whereas work overload (β¯ =0.063, 95% CI 0.001; 0.126) was positively associated with work engagement. The job demands-resources theory is suitable for explaining nurses' work engagement even in times of crisis. Taken together, key resources and demands have a significant influence on nurses' work engagement under pandemic conditions. However, not all so-called key resources and demands actually have a key status in a pandemic. Any lack of formal rewards should be countered, professional resources should be sustainably secured, and the autonomy of nurses and their interpersonal relationships should be strengthened. Nursing management decisions should be made not only with the current pandemic but also the post-pandemic period in mind.