Mobile learning (mlearning) is an emerging trend in schools, utilizing mobile technologies that offer the greatest amount of flexibility in teaching and learning. Researchers have found that one of the main barriers to effective mlearning in schools is the lack of teacher professional development. Results from a needs-assessment survey and a post-workshop evaluation survey describe the professional development needs of teachers, technology coaches and administrators implementing an mlearning initiative in K-12 schools across 21 US states. Generally, needs shifted from a focus on technology integration and pedagogical coaching to a focus on the needs for ongoing support and time, reflecting a growing confidence in teachers to develop and implement mlearning lessons. Additionally, results from the needs assessment indicated that teachers and staff feel less confident about external areas such as support policies and community involvement--these areas may also offer areas for future growth in mlearning professional development.