At some point between 1583 and 1584 Sidney began revising the Old Arcadia. By the time he abandoned the text prior to travelling to the Netherlands in November 1585, leaving the manuscript with Greville, he had made radical changes to the structure and tone of his ‘toyfull book’. Although he only completed reworking two and a half of the original five books the revised material was over 50,000 words longer than the completed Old Arcadia. The New Arcadia preserves the interaction of poetry and prose found in the original but, although Sidney reorders and reassigns some of the incidental pieces, he composes few new poems for the revised version.

Even before revision begins there are suggestions of a work like the New Arcadia within the earlier version: narratorial asides promise to return at a later point to the complex back-story of Erona's capture and defer recitation of the princes’ valiant acts beyond Arcadia to ‘a work for a higher style than mine’ (OA 10). Further hints of narrative material concerning events in Arcadia conclude the Old Arcadia, possibly alluding to an unfinished fifth set of eclogues, and suggest that somebody else tells, amongst other things, of the ‘strange continuance’ of Klaius and Strephon's desire (OA 361). Klaius and Strephon appear earlier in the fourth eclogues where Sidney declares it ‘would require a whole book to recount their sorrows and the strange causes of their sorrows’ and tell of their shared love for Urania (OA 284-5). Sidney never goes that far, but the pair do feature in perhaps the first example of a reworking of the Arcadian matter, the unfinished Lamon's Tale, composed around 1581. As a suggestive illustration of how further narrative threads could and would be spun out of Sidney's original story and rewoven into the New Arcadia, the pair reappear in the revised version's opening scene, again complaining of their mistress's absence.

Sidney makes many different kinds of changes to his original text and the New Arcadia represents a total transformation of both the type of story he sets out to tell and how it is told. It is no longer presented within the generic matrix of pastoral comedy but instead, from the outset, has all of the trappings of heroic romance - battles, jousts, duels and sieges - and bears a greater affinity to Sidney's Hellenistic, Spanish and Italian romance-epic sources.