In 1792, Vassa married Susannah Cullen, an English woman from Cambridgeshire. The couple probably met in 1789, while Vassa was selling and promoting his book, of which Susannah was a subscriber. They married in St Andrew's Church, Soham, Cambridgeshire, in April, and the happy occasion was announced in the Cambridge Chronicle and Journal. After the wedding, Susannah accompanied Vassa on his book tours and meetings with fellow abolitionists. They had two daughters, Anna Maria (b.1793) and Joanna (b.1795). Susannah died in 1796 after a protracted illness, both Anna Maria (21 July) and Vassa (31 March) died in 1797, and Joanna (later Mrs Bromley) in 1857. There is very little known of Vassa's family life. Vassa's death was announced in the local and national press. 'Tireless campaigning and extensive campaigning had taken their toll' (Osborne, 2007, p. 8). His burial place is still unknown.