In the first part of the workshop, we review the rich suite of methods now available based on mean length data. These include the estimators that assume equilibrium (Beverton-Holt, Ehrhardt-Ault, length-converted catch curve), and non-equilibrium estimators (Gedamke-Hoenig, Then et al., Huynh et al.). In the second part of the workshop, we show participants how to fit the models using the MLZ package in R (available through CRAN online) and how to interpret the results. Participants are encouraged to bring a computer with R, RStudio and the package MLZ installed so they can try using the MLZ package.