In this paper, I sought to examine the representation of the LGBTIQ community and themes in selected Croatian high school textbooks. I begin by defining the relevant terminology and by placing the LGBTIQ population into the Croatian social, but also legal and educational, context. After that, I pinpoint the importance of an inclusive curriculum for the wellbeing of LGBTIQ youth, because curricula directly impact the contents and values presented in textbooks. What follows is an overview of previous research done on this topic, including research from Croatia, Bosnia and Herzegovina, Montenegro, and Norway. The analysis in this paper was done in two stages, quantitatively and qualitatively, on a sample of 26 textbooks, which mostly belong to social sciences and humanities. Textbook subheadings were chosen as units of analysis, with 106 of them found, including their belonging codes, which deal with one of the themes that were defined beforehand. After the quantitative content analysis, the qualitative reflexive thematic analysis followed, through which I dismissed the earlier defined themes and began seeking for certain patterns in the attitudes of the authors of the textbooks, in order to generate my new themes. In total, I generated seven themes that cover the way in which LGBTIQ themes are represented in the 26 textbooks that formed the sample. The conclusion of this research is that LGBTIQ themes are covered mostly in a superficial manner, while the most about them can be read in textbooks of elective subjects of Ethics and Religion, which hold conflicting attitudes about the topics at hand. This brings us to a conclusion that there is plenty of space for progress in the visibility of LGBTIQ themes in the textbooks of compulsory Croatian school subjects.