His chief works were the long poem Britannia's Pastorals (1613), and a contribution to The Shepheard's Pipe (1614). Britannia's Pastorals was never finished: in his lifetime Books I & II were published successively in 1613 and 1616. The manuscript of Book III (unfinished) was not published until 1852. The poem is concerned with the loves and woes of Celia, Marina, etc.
To him is due the epitaph for the dowager Countess of Pembroke ("Sidney's sister, Pembroke's mother").