This research entitled “Leading for Achievement: The Highly Proficient Teachers Core Competencies and Instructional Leadership Skills in Enhancing School Performance” was surveyed among the Highly Proficient Teachers at selected Secondary schools in SDO Laguna. It aims to assess the following; first, the Highly Proficient Teachers’ Demographic Profile as to Personal in terms of Age, Gender, Civil Status, Educational Attainment, Specialization, Length of Service, and Seminars and Trainings Attended. Second, the Highly Proficient Teachers’ Demographic as to Professional in terms of Subject Taught, IPCRF Score last School Year, Relevant Duties and Responsibilities, Research Conducted, Number of Mentoring/Coaching/ Technical Assistance to Proficient Teachers. Third, the Highly Proficient Teachers Core Competencies in terms of Self-Management, Teamwork, Professional Ethics, Service Orientation, Result Focus, Innovation. Fourth, the Highly Proficient Teachers Instructional Leadership Skills as to classroom observable in term of Knowledge of Content and Pedagogy, Strategies using HOTS, Management of Classroom, Management of Discipline, Work for Differentiated Instruction, Management of Diverse Learners. Fifth, the Highly Proficient Teachers’ Instructional Leadership Skills as to non-classroom observable in terms of Performance for Learning environment, Curriculum and Planning, Assessment and Reporting, Community Linkages, Personality Growth and Professional Development. Sixth, the level of the School Performance of selected schools in the Division of Laguna as to Learners’ Mastery Level, Learners’ MPS, Master teachers’ IPCRF, School’s OPCRF, Awards and Recognition received, and SBM level attained. Seventh, to find the relationship between the Highly Proficient Teachers’ Demographic Profile as to Personal and Professional, Core Competencies, Instructional Leadership Skills as to classroom observable and non-classroom observable and School Performance. This research used descriptive research design through a survey questionnaire for Highly Proficient Teachers and School Heads as the source of data. The respondents were the161 Highly Proficient Teachers from Medium and Large Secondary Schools in the Division of Laguna. It utilized a constructed survey questionnaire based on the related literature survey and the PRMS PPST indicators for Highly Proficient Teachers. Each indicator of the variables is composed of five parametrical items. Part I of the questionnaire was intended for the Highly Proficient Teachers through profiling their Personal and Professional status while Part II is about their Core Competencies in terms of Self-management, Teamwork skills, practice of Professional eEhics, Orientation to Services, Results-Focus, and ability to Innovate. Part III is the respondent’s Instructional Leadership Skills including knowledge of Content and Pedagogy, Strategies using HOTS, Classroom Management, Learners’ Behavior Management, Diverse Learners’ Management, Ability to Create Safe and Secure Learning Environment, Curriculum Planning, Assessment and Reporting, Community Linkages, Personal and Professional Growth, and Professional Engagement. Part IV is the School Performances as to Learners’ Mastery Level, Learners Mean Percentage Score, Average IPCRF of Teachers, the OPCRF, the School’s Awards and Recognition received by the School, and the Assessed SBM Level of the School were harvested. Likert Scale was used to interpret data. Therefore, the research postulates that there is a significant relationship between the Highly Proficient Teachers’ Demographic Profile as to Personal and Professional, Core Competencies, Instructional Leadership Skills as to classroom observable and non-classroom observable and School Performance, thus the null hypothesis is rejected. This suggests that on the aspects of school management there must be an enhanced Highly Proficient Teachers’ Development Program as to assessment of learning achievement, developing higher order thinking skills, research, seminars, and trainings be reinforced.