Recently, there has been growing attention on behalf of both 9 academic and practice communities towards the ability of 10 Artificial Intelligence (AI) systems to operate responsibly and 11 ethically. As a result, a plethora of frameworks and guide- 12 lines have appeared to support practitioners in implementing 13 Trustworthy AI applications (TAI). However, little research 14 has been done to investigate whether such frameworks are 15 being used and how. In this work, we study the vision AI 16 practitioners have on TAI principles, how they address them, 17 and what they would like to have – in terms of tools, knowl- 18 edge, or guidelines – when they attempt to incorporate such 19 principles into the systems they develop. Through a survey 20 and semi-structured interviews, we systematically investi- 21 gated practitioners’ challenges and needs in developing TAI 22 systems. Based on these practical findings, we highlight rec- 23 ommendations to help AI practitioners develop Trustworthy 24 AI applications.