This paper begins with an account of the various measures for promoting the professional development of teachers and principals as the complementary strategy of the Hong Kong government when it introduced a new accountability framework in 2003. Then, drawing on the evidence derived from a landmark study in Hong Kong secondary schools that looked into the impact of principal leadership on student outcomes using both cognitive and affective data, this paper presents part of the findings that showed how principals also tend to emphasise the professional development of teachers and key staff as a way to strengthen alignment within the school and between school and government policies. Specifically, this leadership dimension was most highly correlated with the dependable variable, the school condition Alignment, Coherence and Structure. Using hierarchical multiple regression, this leadership dimension was also found contributed to about 20% of the variance. This paper further seeks for evidence in interviews with principals and their key staff to explore the significance of professional development in schools demonstrated continuous significant school improvement. Teachers reported that their principals could succeed to align school policies with the contextual demands imposed on the schools, such as medium of instruction policy and the New Curriculum Structure by setting goals for teaching and learning. While these principals could enhance teachers' aspirations and translate meanings for their work, teachers' achievements in administration and teaching further strengthened their confidence and reinforced their participations. Many current key staff teachers who took up new, and more, duties were not necessary those teachers who were previously responsible for more formal roles such as vice principals. Many effective principals reported that they led their staff to meet strategic goals in an accountability context by mentoring and training and development. This builds up