Arayat is now considered as one of the busiest and progressive towns of Pampanga. After the Mt. Pinatubo eruption and lahar mudflows, Arayat was considered by PHILVOCS  as the safest place in Pampanga. Because of this, thousand of migrants flocked the town. Several housing subdivisions were built such as Mountainview Village, Villa Sto.Niño I and II, Villa De San Antonio, to name few. Business inventors continue to rise. The town's progress triggered an increase on its population. Public school is always faced with a dilemma, of having 70-75 pupils per class. The sole private school in the town is so small to accommodate many pupils. This made Arayat a growing community complemented with educational needs of increasing number of residents. Due to this urgent need for a well organized comprehensive and innovative school, not only in Arayat but also in nearby town. Adelle Grace Montessori School Incorporated, was established in the year 1998. The major proponent of the project is Mrs. Adela V. Rivera, a retired Master Teacher I of Arayat Central School, Pampanga assisted by the competent and qualified Montessori teachers. What makes it an ideal place where such center will be put up is the fact that it is strategically located and therefore very accessible to all its expected clients. Adelle Grace Montessori operated Pre-Elementary Education on its initial year that is then formerly known as Adelle Grace Pre-School. The Pre-School Department was further classified into 3 levels namely Casa, Junior Casa, and Advanced Casa which started with only 40 pupils. In consideration of the vital reality that psychologists revealed that 95% of the mental faculties are fully developed in normal individuals during the first five years of their lives, early education can therefore be substantial as server of early intellectual stimulation as provided to them.The grade school was opened on the succeeding year. Two grade levels were added every year. As it is believed, children in the elementary years (6-12) are capable of accomplishing a great deal of mental work. It is their "years of plenty" and given the right opportunities and the right means, they will lay up a great store of culture information. Thus, providing an elementary child with a good and strong educational foundation further ensures success in his future life. As the school's achievement, in 2002 the presented its first batch of elementary graduatesClamor on the part of the parents of the pupils in Grade VI to continue providing instruction for Secondary level adopting the style and system  of the instruction we started in the elementary leve, kept rising . In the year 2002, Adelle Grace Montessori School Incorporated offered Secondary Course  adopting the system of instructions patterned with the Department of Education, its Curriculum and Program.This is th period of "tranformation". In this period, the valorization of the of the personalityoccurs that by the time the individual enters adulthood, he is confident of himself and his capabilities. AGMSI address it as the Professional HIgh School. It is in the School Year 2004-2005 when AGMSI completed its Secondary Courses and finally had its first batch of high school graduates. The High School Curriculum does not only provide academic preperation for college but also special training skills in business occupation, leadership and citizenship. In the year 2010, AGMSI was extended and had its first branch in Sta. Ana, Pampanga. It offers Pre-school Education and SPED Program which caters students with special needs. In 2018, AGMSI Main Campus had its first batch of Senior High School Graduates consisting of 138 students who completed the program for the K to 12 curriculum. As the school moves ahead, AGMSI hopes to live long and contribute more for the benifit of our society, betterment of the new generation and for the greater glory of our Creator.