Multi-domain operations (MDO) can present many challenges for training. Involvement of various disparate organizations and services can exasperate these challenges and can require balancing centralized coordination with decentralized training objectives. Furthermore, although the underlying concept of MDO is not new, the actual term was just recently introduced by the U.S. Army as a doctrinal concept. Consequently, there is a risk that the development of training technology can be reactionary, resulting in siloed efforts. Emerging training technologies can help support the unique complexities of MDO, but the development of these technologies and related systems may need to occur in concert with doctrine development, align with tracing processes, and incorporate input from end users as early as possible. If MDO is to provide new benefits, the training community may need to solve old problems. It may need to communicate more effectively.