Zegarra O. and Alarcón L.F. (2023). What is the complexity of production planning and control?. Proceedings of the 31 st Annual Conference of the International Group for Lean Construction (IGLC31), 1149–1159. doi.org/10.24928/2023/0122 Production Planning and Control 1149 WHAT IS THE COMPLEXITY OF PRODUCTION PLANNING AND CONTROL? Omar Zegarra 1 and Luis Fernando Alarcón 2 ABSTRACT Questionable project performance is a common issue in the Architecture, Engineering and Construction industry, with one contributing factor being the degree of difficulty or complexity of the project. One effective approach to address this issue is to improve the system of production planning and control (PP&C). This strategy, as per the literature, had evolved to include up to four different types of PP&C mechanisms that are related to ´business´, ´production´, ´virtual´, and ´complex´ aspects. Nonetheless, despite the progress, PP&C still disregards various complexity-related aspects. To address this issue, we analyzed the concept of the ´Complexity of PP&C´. This paper discusses its definition, elements, and role. It was found PP&C complexity involves three aspects: project complexity, outcomes complexity, and structural complexity. Thus, we conceptualized PP&C complexity as a feature of the behaviour of outcomes that emerge to answer project stimulus driven by the interaction between the elements of the structure of PP&C, a feature that is both a risk and an opportunity for performance improvement. This perspective offers new insights for PP&C evolution and improvement, although further work is still required. KEYWORDS Production planning and control, complexity. INTRODUCTION Projects in the architecture, engineering, and construction industry frequently demonstrate poor performance. For example, Flyvbjerg et al., (2003, 2004) studied a sample of 258 infrastructure projects worth US$90 billion and found persistent cost escalations of between 20% and 45% that were strongly correlated with the duration of the project implementation. In this regard, one significant factor that contributes to project duration is complexity. It influences negatively performance, as noted by Baccarini (1996), Floricel et al. (2016), Luo et al. (2017), and Williams (1999). For instance, complexity is often understood as the level of difficulty encountered during project implementation, although terms such as challenging, unstable, or unpredictable are also used to characterize it (Brockmann & Girmscheid, 2007; Gidado, 1996; Jarkas, 2017; PMI, 2013). On the other side, one effective strategy to face the poor performance of projects relies on improving the system of Production planning and control (PP&C). The PP&C is a system which aims to transform ´intended´ into ´realized´ outcomes during the project(Ballard & Howell, 1998; Mintzberg, 1978). According to Burbidge, (1990) it “… plans, directs, and controls the material supply and processing activities”. To do so, the PP&C relies on the use of a mechanism implemented using a set of managerial processes (e.g., planning procedures, meetings, 1 Doctor of Engineering Science, Department of Construction Management Pontificia Universidad Católica de Chile, E-mail: ozegarra@uc.cl, orcid.org/0000-0001-7811-7637 2 PhD, Professor, Dep. of Construction Management Pontificia Universidad Católica de Chile, E-mail: lalarcon@ing.puc.cl, (56 2) 354-4201, (56 2) 354 4244, orcid.org/0000-0002-9277-2272