An understanding of private forest owners is needed for appropriate forest governance and outreach to forest owners. This study examined different types of objective and subjective knowledge (i.e., actual knowledge and confidence, respectively), including general forest knowledge and knowledge of management for different objectives, among individual private forest owners in Sweden. In addition, the importance of structural variables (e.g., gender, size of forest holding) and forest involvement variables (e.g., certification, involvement in forest planning) for forest knowledge was analysed. The study was conducted by means of a postal questionnaire to a random sample of private forest owners in Sweden (n = 3000, response rate 43%). Structural variables, but particularly involvement variables, were found to be related to subjective and objective knowledge. Being a male owner, owning a larger forest holding, having bought the land, and having owned the forest a long time were associated with higher subjective knowledge, or confidence, in managing the forest. Although being a male owner, for example, was also associated with higher levels of objective knowledge, the correlation diminished when controlling for forest involvement. The study considers the role of learning environments for forest owners and highlights the need to elaborate on the conceptualization and measurement of forest knowledge to understand the links between structural characteristics, forest involvement, and forest knowledge among private forest owners.