KIIS assesses the psychological well-being of the Ukrainian population in two dimensions: first, the overall satisfaction with life and some of its aspects (such as family, personal life, relationships, work, financial security, environment etc.), and second, self-assessment of happiness. Satisfaction with life in KIIS surveys is measured by the question "Please tell me to what extent you are satisfied or dissatisfied with how your life is going overall?" with a 5-point scale from 1 (Not at all satisfied) to 5 (Completely satisfied), and an additional option "It does not matter to me". This question usually summarizes a set of questions about the respondent's satisfaction with various aspects of life. The list of aspects assessed changed over time. In the surveys since 2013, this list has typically included 17 aspects, namely: family; behavior and personal development of children (if have); personal (intimate) life; relationships with the people around; own behavior towards the people around; own knowledge, experience, and skills; existing possibility of being independent; existing possibility to influence what happens to them; existing possibility of participating in public life; job (if have); level of material well-being; opportunity to realize abilities; living conditions; state of the natural environment in the settlement; economic situation in Ukraine; ensuring the security of Ukraine; level of confidence in the future. Overall, the data collected so far covers the period from 1995 to 2019, and includes 24 waves of nationally representative surveys. To assess happiness, the question "Do you consider yourself a happy person?" with five response options ("yes", "rather yes than no", "both yes and no", "rather no than yes", "no") is employed. This question has been included in KIIS omnibus surveys since 2001, typically once a year. From 2001 to 2023, a total of 24 waves of the survey were conducted. All these survey waves were conducted with a sample representative of Ukraine's adult population aged 18 and older, with an average sample size of about 2,000 respondents. Data on self-reported psychological well-being collected between 1995 and 2023 were merged into a single dataset, including 39 polls with a total of 79,500 respondents. The background information includes respondents' socio-demographic profiles (gender, age, education, nationality, occupation, self-assessment of financial situation) and place of residence (oblast, type of settlement). These data make it possible to track changes in psychological well-being over time and explore some of the factors that influence it, both among the overall population of Ukraine and among different population groups.