On April 29, 1939, the First Aid Unit of Princeton Engine Company No. 1 was officially formed. Headquartered at Engine Company No. 1 on Chestnut Street, it operated out of a station wagon with first aid supplies donated by Johnson & Johnson. Financial assistance was provided by the Fire Company and other interested individuals.

The original first aid committee was discharged in the Summer of 1939, and on March 5, 1940, the Princeton Engine Company No. 1 First Aid Unit was incorporated. The Unit's first ambulance, a 1941 Cadillac, was purchased the following year from Southard S. Mather at a cost of $3,500. The new ambulance made its debut at the annual July 4th fireworks display at Palmer Stadium. Following the vehicle's commissioning, First Aid Unit members began sleeping-in at the firehouse to ensure the availability of prompt, 24-hour coverage for the greater Princeton area at no cost to the patient. Shortly thereafter, the ambulance services offered since 1926 by local funeral directors, Ralph E. Kimble and Southard S. Mather, were discontinued. Those services had charged patients up to five dollars for a trip to the hospital. Also in July, the First Aid Unit joined the New Jersey State First Aid Council's Second District, becoming that organization's eightieth member squad.

Declining membership through the war years prompted the First Aid Unit to open its ranks to those outside Engine Company No. 1. In the Fall of 1941, Albert Toto became the first non-firefighter member of the First Aid Unit. Calls continued to increase in number and additional equipment became necessary. By September 1941, the First Aid Unit had responded to 30 calls, driven 400 miles, and logged 70 man-hours. The number of calls grew to 85 by November and continued to grow into the next year with the First Aid Unit responding to 279 calls and traveling 4,089 miles in 1942.

Contributions from local citizens and business groups became the primary means of financing equipment purchases and associated maintenance costs. By 1951, the original ambulance required replacing, and a Packard ambulance was purchased from John Sylvester at a cost of $7,345. In that year, the First Aid Unit answered 534 calls for service and its members donated 1,362 hours to the community. Following a tragic drowning accident on Lake Carnegie in August of 1955, the Lions Club of Princeton donated a fourteen-foot boat, trailer and water rescue/recovery equipment. A year later, twenty-six Princeton residents, led by H. C. Sturhahn, donated a fully-equipped Ford Stand-Up Van, which became the First Aid Unit's first rescue truck. On May 20, 1957, the First Aid Unit was renamed the Princeton First Aid and Rescue Squad, Incorporated and became one of the first rescue units in the state of New Jersey. The Squad's fleet grew in May of 1960, with the addition of a custom-built Lincoln ambulance from Nassau-Conover and the Ford Motor Company. (Ford built that vehicle as a prototype for future ambulance manufacturing, but it was eventually replaced in 1962 by a Cadillac because of extensive electrical problems.) Later that year, on August 26, 1960, the Ladies' Auxiliary of the Princeton First Aid and Rescue Squad was incorporated. Further equipment acquisitions necessitated additional housing facilities, so in 1961, the Squad purchased land for a new building on North Harrison Street. Contracts were signed in 1962 with architect George F. Lewis and the Lewis C. Bowers Construction Company, and ground was broken.

As the surrounding area grew, and before neighboring communities founded squads of their own, Princeton First Aid and Rescue Squad answered calls within a one-hundred square mile area, covering Princeton, Kingston, Kendall Park, Plainsboro, and parts of East Windsor, West Windsor, Lawrence and Montgomery Townships. In May of 1963, Princeton First Aid and Rescue Squad left Engine Company No. 1 to be housed in its newly completed headquarters on North Harrison Street. The building was dedicated on April 12, 1964, and the $75,000 Building Fund Drive was achieved.

The Cadet Corps was organized in 1965, to provide young people with the opportunity and the training to become full members of the Squad upon reaching adulthood, and to help increase the Squad's supply of capable senior members. Joseph D. Zuccarrello served as the Squad's first Cadet Corps Captain.

A new $35,000 rescue truck, custom built to Squad specifications by Swab Wagon Company, was dedicated on October 1, 1969, and replaced the 1957 Ford Stand-Up Van. The following year, Swab manufactured the first modular-type ambulance in New Jersey for the Squad. This new ambulance design greatly increased the storage and workspace in the back of the vehicles and quickly became the standard design for the Squad. In 1974, Boice-Steward Construction Company built an addition to the Squad house which provided needed storage space for vehicles and equipment as both the Squad and Princeton continued to grow. Also in that year, a Chevrolet Blazer four-wheel drive vehicle was purchased for pulling the boats and associated water rescue/recovery equipment, and for providing off-road transportation.

In 1977, Pat Bodine, Antonia Bogart, MaryAnne Henderson, and Suzanne Neilson became the Squad's first female members. Also in that year, the Lifemobile Program was activated, establishing Princeton First Aid and Rescue Squad as an Advanced Life Support (ALS) provider. J. Edwin Obert, Jr. was the paramedic on the Squad's first ALS call in November, 1977. The following year, women were elected to positions of leadership within the Squad.

In March of 1980, the Squad purchased another ambulance (G. M. Wolf Modular) for $47,000, bringing the total number to three. Decreased availability of members to respond to daytime calls prompted the initiation of the paid day crew program on May 4, 1980. Diran Dermen and Tom Krisanda became the Squad's first full-time employees. The municipally-funded day crew program guaranteed daytime ambulance coverage for the Princeton community, a problem that had plagued the Squad since its inception. The program was made possible through the efforts of Squad members, the Joint First Aid Committee, the Princeton Medical Center, and concerned local citizens. Increasing numbers of calls and miles driven by the Lifemobile required its replacement in 1984. The Squad's third modular-type G. M. ambulance was purchased from East Coast Emergency Vehicle Builders, Inc. at a cost of $52,000. In late 1984/early 1985, two Squad members were instrumental in the formation of the Health Education and Rescue Training (H.E.A.R.T.) Program at Princeton University. Since the Spring of 1985, this program has taught advanced first aid to more than one hundred people each year and CPR to approximately 200-300 people each year.

Adoption of the County-wide paid paramedic program in 1985 resulted in a decline in the number of ALS calls received by the Squad, and an eventual return over the next two years to solely Basic Life Support (BLS) care provision. During that same period, State educational and training standards were tightened, requiring upgrading of all riding members' skills to Emergency Medical Technician (EMT) level. Acquisition of new computer and video equipment has aided in the training of members to meet those new standards, as well as in the handling of Squad records and correspondence.

The Squad's next additions to its vehicle fleet occurred in 1988, with the acquisition of a $61,000 first-line ambulance from P. L. Custom Body, and a $9,000 Zodiac inflatable pontoon boat with thirty-horsepower motor and trailer. The latter provides greater stability and power than the original boating equipment, and markedly improves safety associated with water rescue/recovery operations. In 1991, the Squad replaced the tired red Swab rescue truck with a Mack MR vehicle also built to the Squad's specifications by PL Custom Body. The new rescue truck was designed to be a self-sufficient unit carrying a command and dispatch center, equipment for vehicle extrication, confined space rescue, ice and water rescue, fireground support and air bottle filling, a 6,000-watt light tower, and much more, all powered by a 25-kilowatt PTO generator.

On April 29, 1993 at 2:23 in the afternoon, the Day Crew, along with five volunteer members, responded to a call for a "possible heart attack" in Palmer Square. On that call, they became the second crew in the State of New Jersey to save a life using the new Cardiac Defibrillators. This new program was the most significant expansion of the Squad's medical capabilities since the termination of the Lifemobile program and allowed Squad members to become certified as EMT-Ds. EMT-Ds are able to treat cardiac arrest with sophisticated devices that analyze cardiac rhythms and attempt literally to shock the patient back to life. Largely because of the crew's efforts, and their EMT-D training, that patient walked out of the hospital two weeks later. Since that time, the Squad has required all Senior Members to be certified as EMT-Ds (ensuring that level of training on every crew) and has carried Defibrillators on the ambulances ever since the program's inception.

PL Custom Body continued to build vehicles for the Squad with three more modular ambulances in 1990, 1994, and 1998. In 2001, the Squad took delivery of its first Medium-duty ambulance. This American LaFrance MedicMaster is built on a Freightliner chassis that is expected to provide the Squad with greater reliability and a longer service life. The retired PL Ambulance replaced by the Freightliner was converted to Special Services unit to provide support at Mass Casualty Incidents and to other large-scale responses. In 1999, the Squad modified a 1992 Township police cruiser to serve as a first-response car. This past year, we replaced that car with a 2000 Crown Victoria that will continue to allow members to rapidly respond from around town. Our current fleet of vehicles also includes the Rescue Truck, a 1997 GMC Suburban mobile-command and utility truck, and a 2001 Zodiac Inflatable Marine unit. This coming September, the Squad will take delivery of a new Heavy Rescue Truck from Pierce Manufacturing to replace our current Rescue Truck. The new unit is designed to carry more equipment and to have that equipment rapidly deployable for the types of incidents to which we respond. The Truck’s independent front suspension, coupled with the design of the passenger compartment, will help to ensure the safety of our members as they respond to Rescue assignments.

The Squad now has more than 60 members from all walks of life. Community members serve along side high school and Princeton University students and continue to maintain the Squad's standards of rapid and skillful emergency care. The Day Crew program continues to serve the community during business hours and supplements the volunteer EMTs who still sleep in the building every night of the year and are always available by pager and radio to respond to emergency calls. The Squad continues to meet the growing yearly call totals with standards of care and response times that meet or exceed national and local standards. It is only through the efforts of generations of capable volunteers and the support of a grateful community that the Squad has been able to celebrate such a proud history.