We start with the literature on the tools for the control of the regulators and interpret this literature in terms of accountability relationships. Consider a given instrument: what kind of accountability mechanism does it trigger? Who is accountable to whom, in what fora and through what procedure? We perform this conceptual reading in terms of accountability for the following regulatory instruments: freedom of information, notice and comment, regulatory impact assessment and substantive judicial review. We then check theoretical predictions against the evidence available. We find gaps between the theorized accountability mechanisms and the cross-national experience, and discuss how to feed-back into theory the cautionary tales provided by empirical findings. We argue that policy instruments do not operate in isolation. They work together in ecologies or mixes. We therefore conclude by making the case for studying accountability effects by looking at ecologies – an argument that has consequences for our understanding of causality.