For my research, I ran several univariate and multivariate ACE models using path specification and now I have to extend these models to do multiple groups (young and old) for these very same analyses. I understand the logic of creating a heterogeneity model first and then equating the estimates for both groups in the homogeneity model. I have been trying to modify the non-ACE multiple groups scripts taken from the OpenMx User guide but I have run into many problems. I also tried Hermine's heterogeneity scripts but I am unfamiliar with the matrix approach and so I haven't had much success with this either. Does anyone out there have a sample multiple- groups script with path specification, either for a univariate or a multivariate ACE that I could look at to model after? Thank you in advance for your help.