Traditionally, computer interfaces have been confined to conventional displays and focused activities. However, as displays become embedded throughout our environment and daily lives, increasing numbers of them must operate on the periphery of our attention. Peripheral displays, ubiquitous computing devices that present information without demanding attention, are difficult to build, particularly because they must dynamically manage the cognitive load they place on users. We have created a toolkit, the Peripheral Display Toolkit (PTK) [5], that focuses on supporting the implementation of peripheral displays. In order to continue to inform future improvements to the toolkit, we conducted interviews of peripheral display designers and developers. Interview results point towards a need for the support of early design decisions, implementation support for gathering and analyzing input, and evaluation. This paper summarizes the interview methodology and results, and discusses the results in search of future research directions.