Schools as social institutions play an important role in contemporary Croatian society, which aims to be a knowledge society. The development of human capital in schools can significantly contribute to achieving a knowledge society because the development of school teachers and education staff also indirectly affects pupils. Perception, attitudes, and knowing how to use ICT are all relevant variables of human capital in a school, given that all those are social contexts and preconditions for the development of a knowledge society. This doctoral thesis provides a theoretical elaboration of two main concepts: (1) human capital and (2) knowledge society. Those concepts are also empirically elaborated in the context of schools in Croatia. Human capital is embodied in the individual. It refers to and is developed by investing in knowledge, skills, formal education, health, and even values such as accuracy and honesty, according to Becker and Coleman (Becker, 1975; Coleman, 1988; 1990). Peter Drucker is responsible for coining the term knowledge society. In that kind of society the focus is on the knowledge worker or expert and knowledge is the main capital of exchange. Knowledge and education are key to a successful career. Knowledge is no longer a private but instead a public good. Extended life expectancy has resulted in a change towards the knowledge society and the knowledge economy. Drucker identifies a distinct relationship between a knowledge society and technology. He claims that new industries and technologies are based on knowledge. He describes knowledge workers, experts or professionals, who produce goods and services containing large amounts of knowledge. Afrić et al. do not equate a knowledge society with a knowledge economy, since a knowledge society is the framework for a knowledge economy. Developed ICT are important in a knowledge society, because they contribute to the simple distribution and easier creation of knowledge (Afrić et al., 2011, 15). This doctoral dissertation aims to contextualize and research conditions and practices that are key to the development of human capital in Croatian schools, with a particular focus on using ICT, as an important precondition for the development of the knowledge society. Therefore, the focus is on human capital in schools in the field of ICT use, considering that ICT is an important element in the knowledge society that we are aspire to. Within this context, the research analyzes formal and non-formal content and forms used to stimulate the development of human capital in Croatian schools. We have examined the attitudes of school staff about ICT usage in their work, perspectives of e-education, as well as determined perceptions about Croatia as a knowledge society. A mixed methodology is applied and several research methods are included: (1) a case study, (2) an online survey, and (3) focus groups. The research respondents comprise 548 school teachers and education staff and 4 schools in Croatia. The research focused both on the level of the individual and the organization, to grasp the complexity of social reality. The case study aimed to analyze the level of the organization – a school in Croatia. Four schools were researched, specifically two primary and two secondary schools. They were selected from different areas of Croatia by purposive sampling, based on the criteria that human capital was presumed to be developed in the field of ICT usage in that school, as well as the perception that the school is better equipped with ICT than other schools. In the selected schools, we interviewed a total of 14 research respondents and also gathered data from various sources. We also conducted field visits and analyzed photographs taken on site. The case study includes an analysis of the school’s official web site, video content, various documents such as the annual school plan and available rulebooks, and several data bases. The other two methods were aimed at the level of the individual, specifically school teachers and education staff in Croatia. An online survey was conducted, which included 511 research respondents and implied a representative and stratified sample. We conducted three focus groups with a total of 23 research respondents from various schools and areas of Croatia, based on convenience sampling. The field research was conducted from October to December 2017. The mixed methodology research was conceptualized to overlap thematically between different research methods, so triangulation of data would be achieved. The aim was to have all three research methods contribute to illustrating the processes, situations, and challenges that developed within the research topic. The case study research results, especially data gathered from the interviews, indicate that the development of human capital in school, professional training, and the actual use of ICT in schools are intertwined topics that the respondents often comment on without distinguishing between them. School staff perceive that their colleagues are attending professional training on a relatively regular basis, and in some schools the motive for attending are pupils. The survey research respondents perceive a commitment to work and motivation, developed expert knowledge, and acquired work experience as their most important advantages in the workplace. The respondents claim to regularly develop their knowledge and skills by reading texts authored by experts in the field or attending various forms of professional training, although the attendance frequency seems to vary. The average frequency of realizing 6 different types of activities for developing knowledge and skills (specifically reading, attending workshops, face-to-face or online courses, lectures, and webinars) is 1–5 and 6–11 times a year, with a relatively smaller mean deviation. Regarding the frequency of these activities and the respondents’ parent school, a statistically significant relationship between variables has been found. Those respondents whose parent school is a primary school more often attend face-toface courses, while those whose parent school is a secondary school more often read texts authored by experts (printed or online). The focus group research respondents state that it is their obligation to attend professional training. They emphasize the importance of motivation and willingness to attend professional training, but also to use ICT. They mostly show no strong preference for either online or faceto-face professional training. It is our impression that the case study respondents have similar ideas about this topic, but we did not aim to research this within the case study. The survey results demonstrate that two thirds of the research respondents completely or partly estimate that their colleagues prefer face-to-face training (e.g. workshop, lecture) rather than online training (e.g. webinar, online course). The focus groups demonstrate various perceptions of professional training availability for the school teachers and education staff. It is our impression that the case study respondents assessed professional training to be more available than did other respondents, but that is in line with the selection criteria for choosing the schools researched within the case study. The schools included in the case study are better equipped with ICT than the average school and possess various specialized ICT (hardware and software), which is also perceived by the school staff that we interviewed. The survey results demonstrate that 70–80% of the respondents are completely or partly satisfied with the availability and the quality of ICT in their school regarding their teaching or non-teaching needs, while about 15% are completely or partly dissatisfied. The interviewed staff in most of the schools researched within the case study asses that ICT in their school is used regularly, probably by most of their colleagues. In only one school do respondents assess that some staff use it, while others do not use it at all. The survey data demonstrate that almost 90% of the respondents claim that they try to use ICT regularly for teaching and non-teaching tasks, and that they cannot imagine administrative tasks at school without ICT. They use ICT more often for personal rather than professional purposes. The focus group respondents are accustomed to ICT usage in the school and they also describe the various challenges that they face in using ICT. The organizational climate in the schools researched within the case study is assessed as positive and encouraging, considering the statements of the interviewed respondents. Such an organizational climate in the school is perceived as relevant for a successful school. These schools have well-established cooperation with various organizations and take part in a variety of projects. Formal awards for school employees do not exist; however, informal ones do. Attending professional training that implies a cost for the school is often perceived and presented as a kind of a reward for the employee. School employees are encouraged to attend professional training and use ICT. Support within the school is considered to be important for the school’s success. The focus group respondents state that they have support to attend professional training. About two thirds of the survey respondents perceive a positive and encouraging social climate in their school. On average, the survey respondents are positive or at least neutral in assessing the contribution of their school to the knowledge society. We have found a statistically significant relationship between these variables and the perception of human capital regarding ICT usage within the school. Therefore, about three out of four respondents who perceive human capital regarding ICT usage within their school to be satisfactory also believe that their school contributes to the development of the knowledge society. The focus group respondents perceive the importance of a school as an institution that should contribute to the development of the knowledge society, and they often state the importance of the teacher in that context. Considering the survey and focus group results, it is concluded that school teachers and education staff are neutral to mildly negative in assessing Croatian society as a knowledge society.