How the name of our barangay got its name are derived from major situations.

1. Geographical Location
2. Biological Abundance
3. What we have and are know for
4. Honor & Tribute to a rich and influencial person

On its northern side, a legendary creek separates the barrio from the municipality of Conclusion. This creek which is now particularly dry, was once upon a time full of water where abounded a particular species of fish, well like in form, which the Chinese found it to be very delicious. This fish is called Kasili. Since at that time there was no name to call the certain place and that during that time Kasili fishes were widely known in the vicinity of the creek, they tend to call the place Kasili. Since we were adulterated by Americans during and after their stay here in the Philippines, upon registering the name of the barangay, the K was dropped from the word and the letter C took its place. That was how Casili got its name. Even the adjacent barangay of Consolacion which is located at the other side of the Kasili creek is also named Casili.