Unweaned calf morbidity remains high; a costly animal welfare concern. A survey of 115 Quebec dairy farmers found mean calf mortality of 8.8 %, which was underestimated by 20-50 % by producers: 94 % believed calf mortality was not a problem. Tools to assess calf health and welfare on-farm are needed. From this survey, we identified 10 areas of concern: calving management, newborn care and painful procedures, colostrum management, calf-dam separation, weaning, calf feeding, calf housing, heifer feeding, heifer housing, and health. We developed a diagnostic and intervention tool with recommended goals for each area of concern. An expert committee validated the scoring system and recommendations. The tool was tested in 28 dairy farms for feasibility, producer satisfaction and repeatability. Farmers were asked to take colostrum and blood samples, and record health data. The on-farm evaluation included an interview on management practices and in-barn measurements related to calf welfare. The efficiency and usefulness of the tool was evaluated by the producers. The visit required 3:38±1:07 h (Mean±SD). We found that 100 % of producers were convinced of the effectiveness of our diagnostic tool for identifying areas in need of improvement, and that our tool was useful as an advisory tool for technical advisors and veterinarians. Involving producers in the collection of data (e.g. checking colostrum quality by using a colostrodoser) and providing realistic targets, helped in putting emphasis on problem areas and in discussing ways of improvement. 75 % of producers would continue using the colostrodoser and keeping stock of colostrum. Although 65 % found it useful to keep health records, only 32 % continued to do so over a 6-month period. Voluntary improvements in animal welfare can be facilitated by using appropriate tools to educate producers and help them change their attitudes towards management and animal welfare.