About

Who wrote lavaan?

The main developer of lavaan is: Yves Rosseel

If you have questions about the use of lavaan, please do not email me directly, but use the discussion group: https://groups.google.com/d/forum/lavaan

Code contributors

Several people have contributed source code to the lavaan project:

• Terrence Jorgensen (see also the semTools and lavaan.mi packages)
• Luc De Wilde (Code clean up and standardization; documentation and testing; transition to snake_case)
• Daniel Oberski (Delta matrix, EPC, github; see also the lavaan.survey package)
• Jarrett Byrnes (sem-additions, Satorra-Bentler, formative constructs)
• Leonard Vanbrabant (the InformationTesting() function and parts of the bootstrapLRT() function; see also the restriktor package)
• Victoria Savalei (R code for missing data and the Yuan-Bentler test statistic)
• Ed Merkle (added type=“yuan” in the bootstrapLavaan() function; see also the blavaan package)
• Michael Hallquist (mplus2lavaan)
• Mijke Rhemtulla (R code for computing the fraction of missing information (fmi))
• Myrsini Katsikatsou (estimator = “PML”)
• Mariska Barendse (lavTablesFitCm, lavTablesFitCp, lavTablesFitCf)
• Nicholas Rockwood (multilevel SEM with random slopes)
• Florian Scharf (ESEM)
• Han Du (estimator = “DLS”)
• Haziq Jamil (PML + weights, RBM estimation)
• Franz Classe (GEE-style scores for WLS with categorical data)

Since June 2026, YR has used Claude (particularly Opus 4.8 and Fable 5) as a development assistant to help identify and fix bugs, and to merge prototype and experimental code into the main lavaan source code as new features.

Thanks

Since the release of version 0.3-1, many people have provided valuable feedback, comments and suggestions. Below is an (incomplete) list of people that somehow contributed to the (early) development of lavaan:

• Anne Boomsma, Joerg Evermann and Jarrett Byrnes tested the early versions and gave valuable feedback (2010)
• Gerhard Arminger provided the MECOSA source code, written in the GAUSS language (2010)
• Rens van de Schoot for allowing me to present at the Mplus user meeting in 2010 and sending Leonard Vanbrabant to Ghent in 2011
• The Psychoco organizers (for inviting me in 2011, leading to the JSS paper in 2012)
• Michael Hallquist (author of the MplusAutomation package, initially used for testing lavaan)
• Sacha Epskamp (author of the qgraph and semPlot packages with great support for lavaan)
• Todd Little for inviting me to Kansas in 2012, where we met Sunthud, Terrence, and Alexander, and where the idea of semTools was born
• Rolf Steyer for inviting me to Jena in 2012, where I met Axel Mayer, and introducing me to EffectLite
• feedback and suggestions from Alberto Maydeu-Olivares, Victoria Savalei, Alexander Robitzsch, Alexander Schoemann, David Kaplan, David Kenny, Paul De Boeck, Michael Eid, Eric Klopp, Felix Schönbrodt, Njål Foldnes, Francis Tuerlinckx, Fred Oswald, Mauricio Garnier-Villarreal, Moritz Heene, Herbert Hoijtink, Holendro Singh, Holger Steinmetz, Jack McArdle, James Grace, James Steiger, Keith Widaman, Kentaro Hayashi, Mikko Rönkkö, Paul Johnson, Irini Moustaki, Sunthud Pornprasertmanit and many, many others.

License

The lavaan package is licensed under the GNU General Public License Version >= 2

Funding

From 2010 until 2026, the lavaan project was not funded, and was solely the work of volunteers. In December 2025, lavaan received funding via an NWO-funded project for Dutch open-science infrastructural development (see this Zenodo page for more information). The project started on 15 June 2026.

Contact

Email: Yves.Rosseel@UGent.be