Ensuring acceptable welfare conditions for animals at the time of slaughter is paramount in meeting legislative and retailer specifications and in producing high quality meat. There is existing evidence that welfare training programmes for members of the farming industry can improve animal welfare and product quality, however, there is limited information on the effects of welfare training in the slaughter industry. This PhD examined the impact of welfare training at slaughter on animal welfare, personnel attitudes and product quality using a mixed methods design. Attitudes of slaughter industry personnel and whether they were influenced by training were assessed using questionnaires and interviews. There was limited evidence that the training courses used throughout the thesis resulted in attitude change, however trainees did report the acquisition of new knowledge. Animal welfare and product quality assessment protocols were developed to assess the impact of introducing a comprehensive welfare training programme in three cattle and two poultry slaughterhouses. Assessments were conducted prior, immediately post and six months post-training. Post-training improvements in welfare measures were seen in all slaughterhouses, particularly when cattle were entering raceways and moving into the stun box, and during bird entry into the water bath. There were less consistent improvements in product quality measures, likely due to the multifactorial nature of carcass quality. Using CCTV to overcome potential observer bias during these assessments was investigated. It is suggested that the effective use of data produced by CCTV and Remote Video Auditing may improve the impact of welfare improvement measures, such as training. Finally, interviews were conducted with slaughter industry personnel which identified economic factors as a significant motivator and barrier to welfare change in the slaughterhouse. The results obtained from this study provide evidence for a positive impact of standardised welfare training and highlight areas which warrant further research.