The main purpose of this study was to determine the effectiveness of the use of classroom observation tool, educational management and teachers` proficiency in the Province of Laguna. This study used a descriptive method of research that involved the participation of two hundred thirty (230) teacher-respondents. The validated survey questionnaire containing ninety (90) items that covered factors related with the RPMS ? Classroom Observation Tool (COT). The level of the conduct of RPMS - Classroom Observation Tool (COT) in terms of feedback and support and in terms of monitoring and coaching were interpreted as highly evident among the respondents in the province of Laguna. The level of educational management as to curriculum, teaching-learning process, school management, organizational funding, and professional development were all attained a verbal interpretation as highly evident among the respondents. Furthermore, the level of teachers` instructional proficiency as to content mastery, instructional design skills, instructional delivery skills, instructional assessment skills, and classroom management were all verbally interpreted as highly evident among the respondents. Moreover, the level of teachers` professional competency as to speakership, as to research, as to awards/recognition, as to chairmanship, and as to coaching and mentoring were all interpreted verbally as highly evident. The findings and the result of the study also revealed that the use of Classroom Observation Tool (COT) in terms of Feedback and support were not observed to have significant effect to the teachers? instructional proficiency and to the teachers? professional competency. Moreover, the monitoring and coaching were also not observed to have significant effect to the teachers? instructional proficiency and professional competency. Therefore, the null hypothesis stating that ?The use of classroom observation tool (COT) has no significant effect on teachers? proficiency in the Province of Laguna? is accepted. On the other hand, in terms of Educational Management, the curriculum was not observed to have significant effect to the teachers? instructional proficiency but was observed to have significant effect to the teachers? professional competency. As to teaching-learning process, it was not observed to have significant effect to the teachers? instructional proficiency as well as to teachers` professional competency. Furthermore, school management were not observed to have significant effect to the teachers? instructional proficiency and to the teachers` professional competency. Moreover, organizational funding was not observed to have significant effect to the teachers? instructional proficiency as well as to the teachers` professional competency. And lastly, in terms of professional development, it was not observed to have significant effect to the teachers? instructional proficiency and to the teachers` professional competency. Therefore, the null hypothesis stating that ?The educational management has no significant effect on teachers? proficiency in the Province of Laguna? is accepted.