Successful planning and implementation are factors essential to effective governance. A school that is governed well results in the effective delivery of basic education services. This explanatory sequential mixed methods study assessed the School Improvement Plan (SIP) implementation in the Muslim Areas of Lanao Del Norte Division. A researcher-made questionnaire gathered quantitative data from the 73 principals who were mostly holders of a masteral degree, had 10 years and above experience, and had Principal I position. The practices in the Assess, Plan, and Act Phases of SIP implementation were fully implemented and the school principals did not meet serious problems that hindered them from implementing the SIP.

Using in-depth interviews of the 10 participants selected using purposive sampling, the qualitative data analyzed using thematic analysis. The qualitative data strengthened, complemented, and explained the quantitative stage, giving a comprehensive analysis of the research problem. Therefore, the implementation of the SIP requires a collaborative effort among the school principals, teachers, SPT, Project Team members, and other stakeholders.

With the proper planning and constant monitoring of the SIP implementation, schools’ performance will surely improve.