As current sustainability challenges are increasingly acknowledged to be of a persistent and systemic nature, sustainability transitions are pursued as likewise systemic solutions. Attempts at such systemic innovations have frequently been seen to become 'captured' by incumbent actors, however. As such neutralizing or even perverting co-optation reveals the tense power relations involved, capture is a key dimension of sustainability transition politics. This article argues that capture need not be considered as undesirable per se, however. Against prevalent idealist understandings, a dialectical understanding of innovation capture is developed. This perspective elicits two often neglected aspects of capture, namely its ambiguity and its longitudinal development. Invoking insights from the sociology of translation, it is highlighted how innovation attempts are translated by situated actors, who strategically emphasize or downplay the elements of the innovation that fit their ambitions. Through the typical alternation of radicalizing and domesticating appropriations, it is shown how capture may even turn out favourable to capture 'victims' and their envisioned transitions. Comparing four system innovation processes in the Dutch traffic management field, it is shown how transition politics unfold around Trojan horses. Being equipped with latent transformative force, these seemingly innocuous innovations are even meant to be captured.