The first session of the Second Continental Congress began on 10 May 1775 and ended officially on 1 August. What went on at the congress, apart from the actions recorded in the printed journal, remains a matter for some conjecture. For the First Congress, one of the best sources is Adams' Diary, but from April to September 1775 the burden of business apparently kept Adams from getting down his impressions and recording debates; there are no entries for this period. Adams' attitude toward the various measures actually adopted by the congress can be gleaned from his letters, but his views while measures were being debated are unrecorded. The number and content of his letters make them a valuable mine of information, long recognized. Of the members' letters printed by Burnett for this session, approximately 21 percent are by Adams ( Letters of Members , 1:89–186). His Autobiography contains what are really the only accounts of his position on the appointment of George Washington as commander in chief, on the necessity for the colonies to take over the powers of civil government, and on the monumental dispute with John Dickinson over the second petition to the King and the whole question of reconciliation ( Diary and Autobiography , 3:314–325, 351–354). The Autobiography, however, suffers somewhat from hindsight, for these sections were written in 1805.

Adams served on nine committees during the first session. Because no evidence has been found to determine the exact role he played on these committees, his service can most usefully be presented in tabular form, showing the dates of appointment, the members with whom he served, and the dates and availability of reports.

In addition to his committee work, Adams signed along with other members of the congress the second or Olive Branch petition to the King of 1 Sept. 1775, although he thought the gesture futile, even inimical to the colonies' best interests. Adams' major role was played on the floor of the congress in the debates over the state of America that began on 16 May. The outbreak of fighting in Massachusetts had convinced him that the congress would have to take supportive action. Specifically, he wanted it to assume responsibility for the army at Cambridge and to increase defensive measures. He held that negotiation with Great Britain from a position of strength made much more sense than attempted reconciliation through petition and addresses. Impatient as he was for firm measures, he recognized that the congress would move slowly, for it reflected the mood of the people (JA to James Warren, 6, 11 July, below). Adams' opposition to reconciliation and his support for resistance made him one of the leaders of the group that would ultimately push for independence.