As when joining fields in ArcMap, the Add Join tool only accepts in-memory layers that reference geographic data stored in a data source.

To join a DBF table to the vegtypelayer (in-memory layer), expand the Data Management Tools toolbox, then expand the Joins toolset. Right-click Add Join and click Open.

Notice that all required parameters in the Add Join dialog box need values set for them. There are green circles next to these parameters, indicating that a value needs to be specified for each.

Click the dropdown arrow and click vegtypelayer to use the created in-memory layer as the value for the Layer Name or Table View parameter.

The Add Join tool appends attributes from one table to another using a common field. Here, the common field is named the same in the layer and in the table (HOLLAND95).

Click the dropdown arrow for the Input Join Field parameter and click HOLLAND95. Type “vegtable.dbf” for the value of the Join Table parameter. The path to the current workspace is supplied for you when you click another parameter. Click the dropdown arrow for the Output Join Field parameter and click HOLLAND95. Leave the default Keep All to retain all records in the result. Click OK.

Vegtypelayer will now contain two fields: HABITAT and VEG_TYPE.