On December 6, 1849, Franklin College and Marshall College began to explore the possibility of a merger as a method to secure the future of both institutions. Three years later, on June 7, 1853, the combined college was formally dedicated at Lancaster's Fulton Hall. The merger created an all-male Reformed Church institution that combined the resources of both schools. James Buchanan, four years shy of becoming the 15th President of the United States, was named president of the first Franklin & Marshall board of trustees.
The college’s first two presidents, Emanuel Vogel Gerhart, a Marshall College graduate, and Nevin struggled to keep the young school afloat with an inadequate endowment. But the hope of creating a reputable liberal arts institution fueled their efforts to push on. “No second- or third-rate school will do,” said Nevin at the formal dedication of the united college. “We must either have no college at all or else have one that may be in all respects worthy of the name.”
On May 16, 1856, Franklin and Marshall College dedicated its main building, "Recitation Hall." The distinctive, tall-towered structure, designed in the Gothic Revival style, was constructed on "Gallows Hill," the former site of Lancaster's public executions and the highest point of ground in the city. At the laying of the building's cornerstone in 1853, Henry Harbaugh, a Marshall College graduate and pastor of the Reformed Church of Lancaster noted that the city's lowest point was the location of the Lancaster County Prison. Harbaugh stated: "Thank God! The College stands higher than the jail. Education should be lifted up and let crime sink to the lowest depths!" Recitation Hall came to be known as Old Main and the ground as College Hill.
Franklin and Marshall College took as its motto the Latin phrase "Lux et Lex", which translates in English to "Light and Law". This was the reverse of the Marshall College motto "Lex et Lux". While legend has it that the switch was the result of an error by an engraver, it was more likely a deliberate decision to pair the words with its founders Benjamin Franklin ("light") and John Marshall ("law").
The college seal depicts the profiles of Franklin and Marshall, both looking to the left. It has been often suggested that this represented the two leaders looking westward towards the (then) future expansion of the United States. Despite the fact that his name comes second, John Marshall is shown on the left of the seal and Benjamin Franklin is on the right. But Franklin's full head is shown, while Marshall's profile is cut off and far in the background. Some say that this shows the college's unspoken tendency to favor Franklin's legacy over Marshall's. Recently this preference became more than simply unspoken, as the school actively promoted recognition of Benjamin Franklin's 300th birthday while ignoring John Marshall's 250th birthday, both of which occurred during the spring semester of 2006. The school only recognized Marshall's milestone birthday after a petition was circulated by then senior Ryan Corbalis and signed by a significant portion of the students and faculty of the college.
Old Main, Goethean Hall, and Diagnothian Hall were added to the National Register of Historic Places in 1975.