The emergence of 'Post-PC” iPads and Galaxy tablets as global heavyweights of mobile technologies have prompted a wave of educational technology advocates and policy makers to encourage teachers in the harnessing of mobile technology into K-12 classrooms. The actual level of implementation, however, has been reported as lagging far behind these research-led initiatives and slowed down the momentum envisaged by these policies, especially in many classrooms in the public sector. Teachers as individual innovation adopters are believed to play a crucial role in this innovation change process for the adoption of mobile technologies. To better understand the reluctance of teachers to adopt these mobile technologies into their classrooms, this study assessed teachers´ concerns over harnessing mobile technology in Hong Kong public sector K-12 classrooms. A total of 159 teachers participated in this study. Utilising the Stage of Concern framework, a mixed-method approach was taken. Data collection compiled self-reported Stage of Concern Questionnaires and Open-Ended Concerns Statement opinion polls. Preliminary descriptive analysis showed that teachers experienced all five categorical concerns over harnessing mobile technology in teaching practices. The Information construct underscored a more intense area of concern. From the findings, implications in terms of accessibility, time, support-related interventions, leadership issues, and further suggested interventions are discussed.