There was plenty of work to do. Andover's seminary and those that were shortly established in its example created a new demand for theological publications meant to be used by faculty to teach their aspiring ministers. The students required grammar books and lexicons in Greek and Hebrew that aided their analyses of the Holy Scriptures in their original languages. That was a big part of what their education was all about. They also needed chrestomathies, i.e., anthologies of literary passages in those same languages meant as aids to study; reprints of British and other religious classics (e.g., Richard Baxter’s The Saints’ Everlasting Rest of 1650); theological treatises; inspirational biographies of the pious deceased; and of course sermons of all types, the best of which seminarians were meant to take as models for their own, upcoming duties in the pulpit.
Flagg and Gould began printing immediately, with the hapless Mark Newman usually listed as "publisher." Perhaps he wasn't so hapless after all. In any case, one of their first printing jobs was a reprint of Britain's Thomas T. Biddulph's Short Sermons Designed for the Use of Those Who Have Little Time to Read Longer Discourses ("Published and Sold by Mark Newman. Flagg and Gould, Printers"). A second was another British work, Reverend William Romaine's A Choice Drop of Honey from the Rock Christ; or, A Short Word of Advice to all Saints and Sinners ("Printed for Mark Newman by Flagg and Gould"). Each title was appropriate reading for members of an ordinary orthodox congregation: e.g., South Church's. Specifically for that parish, they printed Articles of Faith and Forms of Covenant, Adopted by South Church in Andover, To Which is Added the Rev. Samuel Phillips' Answer to the Question, "What Shall We Do, the We May Keep in Mind our Covenant?"
In the first year of existence Flagg and Gould also printed one book in Hebrew and one in Greek. The two men were undoubtedly exposed to work with fonts in those languages while apprenticed to Hilliard. The experience may be yet another reason why they were set up with the shop in Andover. They did not have to understand the languages themselves to work with them. As was noted in 1833 by the early nineteenth-century publication The Printer: "A knowledge of languages is useful but not absolutely necessary, as with care a compositor can follow an author's copy even when he doe snot understand the language in which it is written." 
The Greek book was a reprint of A Harmony in Greek of the Gospels, with Notes by Dublin's William Newcombe. It was bound along with Select Readings by [Johann Jakob] Griesbach, by the Junior Class in the Theological Seminary of Andover, under the Superintendance [sic] of Moses Stuart. The Hebrew volume, an original work, was by Professor Stuart. Purportedly it was typeset from handwritten notes he used to lecture to his classes. On December 12, 1813, he sent a copy of the book to Eliphalet Pearson and asked for his opinion about it: “I shall place much dependence on your Remarks. Please to write them down.” Happily for book history, since such information is often unobtainable, he mentioned to “Dr. Pearson” the number of copies printed: “only about 120.”  Given the book’s rarity, it’s no wonder a copy cannot be located in institutional collections, but there is a record of one having been put on loan exhibition in Boston’s Copley Hall in April of 1897 by the Andover chapter of the Daughters of the American Revolution. The exhibition was part of the city’s commemoration of the Battle of Lexington and Concord. In addition to objects with vague dates and provenances, such as “Candle snuffers, known to be very old” and “Very old wine glass,” the D.A.R. members and their friends lent ones with more complete and compelling descriptions, for example, “Writing paper manufactured at Andover by Phillips & Houghton in 1790.” The copy is described in the exhibition catalog as: “Hebrew Grammar without points, by Professor Moses Stuart. Published in Andover by Flagg and Gould, 1813… [Lender] Warren F. Draper.” 
In 1814 Flagg and Gould printed another original work, An Account of the Massachusetts Society for Promoting Christian Knowledge, Pearson's pet organization, which favored the printing and distribution of tracts. The book included regional reports. The one for Maine said that, because missionaries and tracts were being sent there, “this section of the country [had] been delivered from the jaws of sectarianism.” Missionaries were, likewise, being sent to New York State and Rhode Island, and a “sleigh load” of tracts [had] been taken to New Hampshire to be distributed around “Lake Winnipissiogee [sic].” According to the society's accounting, it had circulated 6,253 tracts in 1804; 9,174 in 1806; and by 1815, it had printed 8,224 books and 30,335 tracts.  But of course the rest of the whole wide world was yet to be conquered for Christ, and there was a deadline: the millennium.
1. Richard-Gabriel Rummonds, Nineteenth-Century Printing Practices and The Iron Handpress, 2 Vols. (Newcastle, Delaware, and London: Oak Knoll Press and The British Library, in association with Five Roses Press, 2004), I, 9.
2. The Andover Center for History and Culture owns the apprenticeship papers of Timothy Flagg. They are the proof that he studied with Hilliard. That Gould did, too, is highly likely and often asserted, but not proven by known paper documentation. We know that Galen Ware apprenticed with Hilliard, too, because, as I discovered, he was one of the witnesses who signed the Flagg papers.
3. The source is Scott H. Paradise, A History of Printing in Andover, Massachusetts (Andover, MA: The Andover Press, 1931). This forty-page monograph was written by a P.A. graduate (class of 1910) and, later, instructor of English from 1925 to 1956. Often cited, it is, however, an exaggerated, error-filled account. See my post "A Needed Correction to the Record" for more information.
4. Quoted in Rummonds, 43, from The Printer, 1833, published by Houston & Stoneman, part of its “Industrial Library.”
5. The letter to Eliphalet Pearson is quoted, without reference to a source, in D. Hamilton Hurd, ed., History of Essex County, Massachusetts, with biographical sketches of many of its pioneers and prominent men (Philadelphia: J. W. Lewis & Co., 1888), 1635. Note: Reverend Charles Smith, pastor of Andover’s South Church in 1852-1853 and again from 1861 to 1876, was the author of the Andover section of this book.
6. Catalogue of a Loan Collection of Ancient and Historic Articles Exhibited by Daughters of the Revolution of the Commonwealth of Massachusetts. Boston, Copley Hall, April 19, 20, 21, 1897 (Andover: Andover Press, 1897), 104. Warren F. Draper was another of Andover’s early printers, active from 1849 until his death in 1905. There will be much more written here about Draper later.
7. A Brief History of the American Tract Society (Boston: The American Tract Society, 1857), 5.