Purpose: The objective of this paper is to inquire into the network structure of publicly financed research collaboration, which Polish scientific institutions undertake with their commercial and non-commercial partners from a multilevel perspective (international, domestic, and intra-regional one). Design/Methodology/Approach: Data collected from the POL-on was used. There were identified 97 publicly financed scientific inter-organizational projects launched in 2019. Social network analysis was applied: there were recognized components, bi-components, centrality measures were calculated (degree, closeness, betweenness). Findings: Polish scientific institutions conduct cross-sectoral projects at different hierarchical levels, and nearly half of them involve partners from different domestic regions. A trilateral partnership between sectors is visible within international projects, while at domestic and local levels, science collaborates with those sectors separately. Warsaw University of Technology is a dominant entity recognized within the identified network. Practical Implications: The conducted analysis helped describe some effects of the public financing system of Polish science. There were also indicated entities of significant meaning within this network. Particular science sector institutions may apply the research results to their future strategies. Originality/Value: This study enriches the empirical investigation on cross-sectoral research collaboration in Poland (that includes not only university-industry-government linkages but also encompasses other types of scientific, commercial, and non-commercial entities). Moreover, a multilevel perspective was applied.