This report examines the first wave of the INVEST Longitudinal study on wellbeing (ILSW), collected in the spring and summer of 2024. The survey was conducted at the INVEST Research Centre of the University of Turku, and will be repeated in 2025 and 2026. Participants were sampled by a random draw from the Population Register of the Finnish National Population Information Service, but sampling probabilities were stratified by age and gender. The questionnaire was sent to 16 200 persons aged 18-80 living in Finland. The sample included native speakers of Finnish, Swedish and other languages. Some 3299 respondents answered the questionnaire, i.e., the response rate was 20 percent. The sample represents the target population well in relation to gender, region, and main activity. The largest challenges relate to the overrepresentation of highly educated and the underrepresentation of non-Finnish and -Swedish speakers. These patterns, however, are typical in survey research. The survey will be linked to administrative data. Taken together, the data helps to understand how resources, well-being and social attitudes change over time. This information is crucial for addressing challenges and opportunities of the Finnish society.