Philip S. LeSourd is a linguist and an anthropology professor at Indiana University in the United States.
At the instigation of Karl Teeter and later Ken Hale, he spent time residing among the Maliseet and Passamaquoddy communities in Maine, United States and New Brunswick, Canada.
LeSourd, Leavitt, and native Passamaquoddy speaker David Francis, Sr. launched a Maliseet-Passamaquoddy to English dictionary project, which resulted in a published dictionary entitled Kolusuwakonol, about eight years after the project began.
The project has continued since, including with funding by Industry Canada and the National Science Foundation, and has been made available online.
LeSourd has continued actively to research Maliseet-Passamaquoddy and a variety of other Algonquian languages.