He was initiated in Charity Lodge, No. 18, in Troy, New Hampshire, at the age of twenty-five, exalted to the Royal Arch Chapter, Cheshire No. 4, and knighted in the Boston Encampment. He was deputy grand master of the Grand Lodge of Massachusetts, and was one of the six thousand Masons who signed, December 31, 1831, the celebrated "Declaration of the Freemasons of Boston and Vicinity"; and at the fiftieth anniversary of that event, which was celebrated in Boston two years ago, Mr. Wilder responded for the survivors, six of the signers being present. He has received all the Masonic degrees, including the 33d, or highest and last honor of the fraternity. At the World's Masonic Convention, in 1867, at Paris, he was the only delegate from the United States who spoke at the banquet. On the seventh of November, 1849, a festival of the Sons of New Hampshire was celebrated in Boston. The Honorable Daniel Webster presided, and Mr. Wilder was the first vice-president. Fifteen hundred sons of the Granite State were present. The association again met on the twenty-ninth of October, 1852, to participate in the obsequies of Mr. Webster at Faneuil Hall. On this occasion the legislature, and other citizens, of New Hampshire were received at the Lowell railway-station, and were addressed by Mr. Wilder in behalf of sons of that State resident in Boston. The Sons celebrated their second festival, November 2, 1853, at which Mr. Wilder occupied the chair as president, and delivered one of his most eloquent speeches. They assembled again, on June 20, 1861, to receive and welcome a New Hampshire regiment of volunteers, and escort them to the Music Hall, where Mr. Wilder addressed them in a patriotic speech on their departure for the field of battle. The two hundred and twenty-fifth anniversary of the settlement of Dorchester was celebrated on the Fourth of July, 1855. The oration was by Edward Everett; Mr. Wilder presided, and delivered an able address. On the central tablet of the great pavilion was this inscription: "Marshall P. Wilder, president of the day. Blessed is he that turneth the waste places into a garden, and maketh the wilderness to blossom as a rose."