The Step Change consortium presented and discussed (together with external experts Xavier Basagaña from the Barcelona Institute for Global Health representing the CitieS-Health project,and Suvodeep Mazumdar from Sheffield University, representing the ECSA working group “Projects, Data, Tools and Technology”) the key takeaways from the work on its “Citizen Science Initiatives” (CSIs) in regard to “Data Collection" during the project activities. Several major lessons learnt in relation to the widely challenges are listed below, along with some experiences, tested solutions and results: 1. Technical and practical challenges 2. Methodological challenges and related skills gaps 3. Challenges related to the effective use of technology and quality control 4. Challenges related to various influences on the motivation of CS In addition to the CSIs' exchange of experiences and mutual learning from this exercise, we also want others to be able to benefit from our findings. The output paper was prepared by the ZSI team (Carmen Siller, ilse Marschalek, Elke Dall) with inputs from all consortium partners.