This case study analyses data on papers of Croatian authors published in 2017 from four Web of Science Core Collection citation indexes (SCI-EXP, SSCI, AHCI, and ESCI). The primary dataset (5,176 articles and reviews) was divided into two subsets, the open access (OA) subset (2,964 papers) and non-OA subset (2,212 papers). We also used the primary dataset to create a subset of papers published in Croatian journals (1,588) as opposed to foreign ones. All were screened for full-text OA status, journal JCR quartile ranking, journal dominant discipline, and language of publication. OA papers prevailed with 74.4%. Most were available at publisher websites. The percentage of OA papers in Croatian journals was 99.8%. The share of OA papers was the highest in the humanities and social sciences, which also saw the highest share of papers in the Croatian language.