In his "rules of civility" Washington enjoined that "those of high Degree ought to treat" "Artificers & Persons of low Degree" "with affibility & Courtesie, without Arrogancy," and it was a needed lesson to every young Virginian, for, as Jefferson wrote, "the whole commerce between master and slave is a perpetual exercise of the most boisterous passions, the most insulting despotism on the one part, and degrading submissions on the other."

Augustine Washington's will left to his son George "Ten negro Slaves," with an additional share of those "not herein particularly Devised," but all to remain in the possession of Mary Washington until the boy was twenty-one years of age. With his taking possession of the Mount Vernon estate in his twenty-second year eighteen more came under Washington's direction. In 1754 he bought a "fellow" for £40.5, another (Jack) for £52.5, and a negro woman (Clio) for £50. In 1756 he purchased of the governor a negro woman and child for £60, and two years later a fellow (Gregory) for £60.9. In the following year (the year of his marriage) he bought largely: a negro (Will) for £50; another for £60; nine for £406, an average of £45; and a woman (Hannah) and child, £80. In 1762 he added to the number by purchasing seven of Lee Massey for £300 (an average of £43), and two of Colonel Fielding Lewis at £115, or £57.10 apiece. From the estate of Francis Hobbs he bought, in 1764, Ben, £72; Lewis, £36.10; and Sarah, £20. Another fellow, bought of Sarah Alexander, cost him £76; and a negro (Judy) and child, sold by Garvin Corbin, £63. In 1768 Mary Lee sold him two mulattoes (Will and Frank) for £61.15 and £50, respectively; and two boys (negroes), Adam and Frank, for £19 apiece. Five more were purchased in 1772, and after that no more were bought. In 1760 Washington paid tithes on forty-nine slaves, five years later on seventy-eight, in 1770 on eighty-seven, and in 1774 on one hundred and thirty-five; besides which must be included the "dower slaves" of his wife. Soon after this there was an overplus, and Washington in 1778 offered to barter for some land "Negroes, of whom I every day long more to get clear of," and even before this he had learned the economic fact that except on the richest of soils slaves "only add to the Expence."

In 1791 he had one hundred and fifteen "hands" on the Mount Vernon estate, besides house servants, and De Warville, describing his estate in the same year, speaks of his having three hundred negroes. At this time Washington declared that "I never mean (unless some particular circumstance compel me to it) to possess another slave by purchase," but this intention was broken, for "The running off of my cook has been a most inconvenient thing to this family, and what rendered it more disagreeable, is that I had resolved never to become the Master of another slave by purchase, but this resolution I fear I must break. I have endeavored to hire, black or white, but am not yet supplied."

A few more slaves were taken in payment of a debt, but it was from necessity rather than choice, for at this very time Washington had decided that "it is demonstratively clear, that on this Estate (Mount Vernon) I have more working negros by a full moiety, than can be employed to any advantage in the farming system, and I shall never turn Planter thereon. To sell the overplus I cannot, because I am principled against this kind of traffic in the human species. To hire them out, is almost as bad, because they could not be disposed of in families to any advantage, and to disperse the families I have an aversion. What then is to be done? Something must or I shall be ruined; for all the money (in addition to what I raise by crops, and rents) that have been received for Lands, sold within the last four years, to the amount of Fifty thousand dollars, has scarcely been able to keep me afloat." And writing of one set he said, "it would be for my interest to set them free, rather than give them victuals and cloaths."

The loss by runaways was not apparently large. In October, 1760, his ledger contains an item of seven shillings "To the Printing Office ... for Advertising a run-a-way Negro." In 1761 he pays his clergyman, Rev. Mr. Green, "for taking up one of my Runaway Negroes £4." In 1766 rewards are paid for the "taking up" of "Negro Tom" and "Negro Bett." The "taking up of Harry when Runaway" in 1771 cost £1.16. When the British invaded Virginia in 1781, a number escaped or were carried away by the enemy. By the treaty of peace these should have been returned, and their owner wrote, "Some of my own slaves, and those of Mr. Lund Washington who lives at my house may probably be in New York, but I am unable to give you their description—their names being so easily changed, will be fruitless to give you. If by chance you should come at the knowledge of any of them, I will be much obliged by your securing them, so that I may obtain them again."

In 1796 a girl absconded to New England, and Washington made inquiries of a friend as to the possibility of recovering her, adding, "however well disposed I might be to a gradual abolition, or even to an entire emancipation of that description of people (if the latter was in itself practicable) at this moment, it would neither be politic nor just to reward unfaithfulness with a premature preference, and thereby discontent beforehand the minds of all her fellow servants, who, by their steady attachment, are far more deserving than herself of favor," and at this time Washington wrote to a relative, "I am sorry to hear of the loss of your servant; but it is my opinion these elopements will be much more, before they are less frequent; and that the persons making them should never be retained—if they are recovered, as they are sure to contaminate and discontent others."