Partners in Flight (PIF) is a cooperative venture of federal, state, provincial, and territorial agencies, industry, non-governmental organizations, researchers, and many others whose common goal is the conservation of North American birds (www.partnersinflight.org). While PIF has focused primarily on landbirds, it works in conjunction with other bird partners to promote coordinated conservation of all birds. PIF follows an iterative, adaptive planning approach that develops a sound scientific basis for decision-making and a logical process for setting, implementing, and evaluating conservation objectives (Pashley et al. 2000, Rich et al. 2004, Berlanga et al. 2010). The steps include: 1. Assessing conservation vulnerability of all bird species; 2. Identifying species most in need of conservation attention at continental and regional scales; 3. Setting of numerical population objectives for species of continental and regional importance; 4. Identifying conservation needs and recommended actions for species and habitats of importance; 5. Implementing strategies for meeting species and habitat objectives at continental and regional scales; 6. Evaluating success, making revisions, and setting new objectives for the future. The 2017 PIF Handbook on Species Assessment (2017 PIF Handbook) documents assessment rules and scores used in the Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States (Rosenberg et al. 2016) and The State of North America’s Birds 2016 (NABCI 2016). It updates previous versions of the handbook (Panjabi et al. 2012, 2005, 2001) developed to accompany other PIF applications including Saving Our Shared Birds: Partners in Flight Tri-National Vision for Landbird Conservation (Berlanga et al. 2010) and the North American Landbird Conservation Plan (Rich et al. 2004). All current and past scores, data sources, and other related information are contained in databases hosted by the Bird Conservancy of the Rockies. Scores can be viewed online and downloaded as excel files, including archived versions (http://pif.birdconservancy.org/acad). The current accompanying Avian Conservation Assessment Database (ACAD) holds assessment scores and data for all 1585 native and 18 well-established non-native bird species found in mainland North America south to Panama plus adjacent islands and oceans. The taxonomy follows the American Ornithological Society’s 7th Edition Checklist of North and Middle American Birds, including updates though the 57th supplement, published in 2016 (http://checklist.aou.org/). The ACAD builds on archived PIF databases that hosted only data on the 882 landbirds native to Canada, USA and Mexico. This handbook is presented in two principal sections. Part I details the factors and scoring used by PIF to assess the vulnerability of species at continental and regional scales (i.e. step 1 of the planning approach above). Each assessment factor is based on biological criteria that evaluate distinct components of vulnerability throughout the life cycle of each species across its range. Part II describes the process of how the factors and the corresponding scores can be combined to highlight conservation needs (i.e. step 2 of the planning approach above). Both the scores and the process have evolved over time (Hunter et al. 1992, Carter et al. 2000, Panjabi et al. 2001, 2005, 2012) and continue to be updated in response to external review (Beissinger et al. 2000), broad partner expertise, and the emergence of new data and analytical tools.