Deserts cover large areas and support substantial biodiversity; however, like other biomes, they are experiencing biodiversity loss. Monitoring biodiversity trends in deserts is rare, partly because of the logistical challenges of working in remote areas. This is true also in Australia, which has one of the largest and least populated desert areas worldwide, has suffered marked biodiversity loss since European colonisation, and has minimal large-scale biodiversity monitoring. However, Indigenous people of many Traditional Owner groups continue to live in, and care for, these deserts. Over the past two decades, Indigenous ranger groups have been collecting species records by using sign-based surveys, adding to work begun in the 1980s by researchers and government scientists. In sign-based surveys, the presence (or absence) of species is recorded by searching on sandy substrates for tracks, scats, burrows and diggings in a fixed area, or a fixed time. Such surveys combine the tracking skills of Indigenous people with robust analytical methods. Here, we describe a desert-wide project that collated and analysed existing sign-based data to explore its potential for local-, regional- and national-scale biodiversity monitoring. The Arid Zone Monitoring Project also provided guidance about future monitoring designs and data-collection methods for varying survey objectives. The project collated data from 44 groups and individuals, comprising almost 15,000 surveys from over 5300 unique sites, with almost 49,000 detections of 65 native and 11 introduced species, including threatened, and culturally significant species. Despite heterogeneity in survey objectives and data collection methods, we were able to use the collated data to describe species distributions and understand correlates of suitable habitat, investigate temporal trends, and to simulate the monitoring effort required to detect trends in over 25 vertebrate species at regional and national scales. Most importantly, we built a large collaboration, and produced informative maps and analyses, while respecting the intellectual property and diverse aspirations of the project partners. With this foundation in place, a national sign-based monitoring program for medium–large desert vertebrates seems achievable, if accompanied by overarching coordination and survey support, training, standardised data collection, improved sampling design, centralised data curation and storage, and regular communication.