The “Learning Quality Inventory for In-Company Training in VET” (VET-LQI) is a survey instrument aiming for a valid and comprehensive measurement of vocational training quality in companies. The validated instrument comprises 22 short scales with 76 items, enabling a broad approach to the construct of training quality. The survey instrument was developed by conducting a qualitative meta-synthesis of all existing instruments regarding training quality. 43 test instruments were integrated into the general theoretical framework on workplace learning by Tynjälä (2013). Item and confirmatory factor analyses (CFA) indicate satisfactory reflection of all common workplace characteristics regarding validity and reliability. Overall, the VET-LQI overcomes the limited applicability of prior instruments by covering all identified content areas of training quality from the literature. Except for ‘Relevance of Tasks’ (Scale 7), which is still included to maintain a broad coverage of the construct vocational training quality.