Prof. Wil van der Aalst published over 200 journal papers, 550 book chapters and refereed articles in proceedings of international conferences, and 20 books as an author or editor. From his books most notable are "Workflow Management: Model, Methods, and Systems" (with editions in Dutch in 1997 and 2004, in English in 2002 and 2004, in Russian and Chinese in 2004, and in Portuguese in 2009), "Process Mining: Discovery, Conformance and Enhancement of Business Processes" (Springer, 2011, also translated in Chinese in 2014), "Process Mining: Data Science in Action" (Springer, 2016), "Modeling Business Processes: A Petri Net Oriented Approach" (MIT press, 2011), "Modern Business Process Automation: YAWL and its Support Environment" (Springer, 2010), and "Process-Aware Information Systems" (Wiley, 2005, also translated in Chinese in 2008).

Well-know is his work on (a) the modeling and analysis of workflow processes (cf. workflow nets and the seminal soundness notion), (b) workflow patterns (his DAPD paper on the workflow patterns is the most cited paper in the BPM domain and the workflow patterns website www.workflowpatterns.com has been the most visited website on workflow management over the last decade), and (c) process mining (Van der Aalst established an international process mining community). Under his supervision, the ProM tool was developed (cf. www.processmining.org) and he also co-initiated the development of other open-source products such as YAWL, Declare, RapidProM, and Woflan.

In recent years, his research concentrated on process mining. Van der Aalst developed various techniques to discover, monitor and improve processes using event data. Process mining is a relatively young research discipline that lies between machine learning and data mining on the one hand, and process modeling and analysis on the other. He is generally considered to be the founder of the process mining field and together with his team he developed powerful techniques for (automated) process discovery (i.e.extracting process models from event logs) and conformance checking (i.e. monitoring deviations by aligning model and log). Process discovery algorithms need to cope with multiple objectives: replay fitness (ability to reproduce the event log), precision (to avoid underfitting), generalization (to avoid overfitting), and simplicity (Occam’s razor). Conformance checking can be formulated as an optimization problem given a cost function in terms of these objectives. Besides the control-flow perspective, also the resource, data, and time perspectives are taken into account. Recently, Van der Aalst’s team has developed techniques for online/distributed process mining and detecting concept drift in processes. These results have been implemented in ProM, an open-source process mining framework developed by his team with contributions from research groups all over the globe. The ideas and algorithms related to process mining have also been adopted in more than 20 commercial process mining tools, including Disco (Fluxicon), Celonis Process Mining, ProcessGold Enterprise Platform (ProcessGold), ARIS PPM (Software AG), QPR ProcessAnalyzer, minit (Gradient ECM), myInvenio (Cognitive Technology), Perceptive Processing Mining(Lexmark), etc.

His work has been very influential as demonstrated by the many citations and adoption of his ideas in (industrial) software. According to Google Scholar his work has been cited more than 90,000 times and his Hirsch Index is 140. He is a so-called ISI Highly Cited researcher and according to Google Scholar he is one of the highest ranked computer scientists in the world (see for example the Top H-Index for Computer Science and Electronics http://www.guide2research.com/scientists/, the "Palsberg list"  http://www.cs.ucla.edu/palsberg/h-number.html, and the ShanghaiRanking’s Global Ranking of Most Cited Researchers 2016 by Elsevier http://www.shanghairanking.com/The-Most-Cited-ResearchersDeveloped-for-ShanghaiRanking-Global-Ranking-of-Academic-Subjects-2016-by-Elsevier.html).He is generally considered to be the most prolific BPM researcher and highest ranked active Dutch computer scientist.

Prof. Van der Aalst is an elected member of the Koninklijke Nederlandse Akademie van Wetenschappen (Royal Netherlands Academy of Arts and Sciences), the Koninklijke Hollandsche Maatschappij der Wetenschappen (Royal Holland Society of Sciences and Humanities) and Academia Europaea (The Academy of Europe). In 2012 he received an honorary doctorate of Hasselt University (Belgium). In 2013, he was appointed as Distinguished University Professor of TU/e and was awarded an honorary guest professorship at Tsinghua University. In 2015, he also received an honorary professorship from the Higher School of Economics in Moscow.

He is frequently asked as an invited/keynote speaker for the main conferences in the field. Not only scientific conferences in his own research area (CAiSE, Concur, FASE, OTM, ATPN, BPM, RCIS, WODES, IESA, MKWI, PAW, etc.) but also conferences in other domains (e.g., keynotes at medical conferences like Medinfo) and conferences aiming at practitioners (cf. his keynotes at two Gartner BPM Summits).

Van der Aalst (co-)organized about 25 conferences and workshops and was a program committee member of about 190 workshops and conferences. He is a member of important steering committees of international scientific organizations. He started the International Conference Series on Business Process Management. This conference is now the leading conference in his research area and Van der Aalst was the chair of the steering committee of this conference from 2003 until 2018. He is also chair of the IEEE Task Force on Process Mining. Besides serving as a member of several other steering committees, he is also editor/member of the editorial board of 12 journals and book series.

The impact of his work is not restricted to the academic world. Many of his ideas and software products have been adopted in practice. YAWL (workflow system) has been downloaded more than 265,000 times, ProM (process mining tool) has been downloaded more than 150,000 times, and CPN Tools (modeling and simulation tool) has been downloaded more than 85,000 times. Note that these are not commodity tools, but advanced software products related to the business process analysis and enactment. Hence, these numbers are quite remarkable. Moreover, these open-source software tools also served as examples for developers of commercial tools (basically all current process mining tools and the BPM software provided by IBM, SAP, HP, Perceptive, Software AG, and Cordys).

Van der Aalst also inspired many younger researchers and helped them to be successful. For example, over the last decade he successfully supervised more than twenty PhD students. Many of his students received prizes (best paper awards, thesis awards, and prestigious grants), e.g., three of his PhD students won the best thesis award of the KNAW research school BETA (in 2008, 2010, and 2011) and dr. Medeiros won in 2007 prize for the best PhD thesis produced at TU/e across all disciplines. Some of his students also started new innovative software companies, cf. Fluxicon and Futura Process Intelligence (now part of Lexmark).