The present study aims to develop, validate, and cross-validate an instrument measuring three proactive social informal learning activities, namely feedback seeking, help seeking and information seeking. Prior research mainly focused on detecting or measuring the frequency of these seeking behaviours and did not consider whether the information, help or feedback that has been sought was also used. Furthermore, although these seeking behaviours were studied extensively in different research fields, the current study takes a learning perspective and interprets feedback, help and information seeking as learning activities. The questionnaire was completed by a convenient sample of 650 professionals working in higher education, consultancy, retail and food production. We performed an exploratory factor analysis (N = 230 educators) to explore the structure of the questionnaire. This was followed by a confirmatory factor analysis (N = 230 educators) to confirm the structure. Finally, we cross-validated the questionnaire in a sample of business professionals (N = 190) by testing for measurement invariance. The final questionnaire resulted in a five-factor structure measuring the (1) Use of Feedback Seeking, (2) Frequency of Help and Information Seeking, (3) Use of Help seeking, (4) Use of Information Seeking and (5) Frequency of Feedback Seeking. The current study presents a preliminary, yet promising instrument that taps into proactive social informal learning.