I found it hard to find documentation on Spec beyond [1],[2],[3], some of which seem to have changed some syntax since they were written. I've been piecing things together to work out how to set the selected item with the simplest example I could. Even though it turns out pretty simple, I thought I'd share in case it was useful for others that haven't dipped their toes into Spec yet. ComposableModel subclass: #TestSpec instanceVariableNames: 'list text' classVariableNames: '' poolDictionaries: '' category: 'BTCPlay' TestSpec >> initializeWidgets self instantiateModels: #( #list #ListModel ). TestSpec >> getList ^list TestSpec class >> mySpecLayout <spec:#default> ^ SpecLayout composed add:#getList ; yourself. Then from Workspace x := (TestSpec new openWithSpec ; yourself). x getList items: { 1 . 2 . 3 . 4}. x getList setSelectedItem: 2. cheers -ben [1] hal.inria.fr/hal-00759030/PDF/Spec-IWST12-Final.pdfâ [2] https://ci.inria.fr/pharo-contribution/job/PharoForTheEnterprise/lastSuccess... [3] http://hal.inria.fr/docs/00/70/80/67/PDF/SpecTechReport.pdf