Will UNION solve the following question?

[JerryGriffith1]

Will the UNION function get at the following problem?

I have a polygon layer that consists of areas in  a floodplain that are also in an "undeveloped" land use category. 

Now I am also using the information from a land ownership parcels (PARCELS) file, and I want to know which of these undeveloped floodplain polygons are in land parcels that are greater than 40 acres (or any other size).

Will a simple UNION function allow me to get this? 

[DanPatterson_Retired]

Union—Help | ArcGIS Desktop 

retains the attributes of both files.  You then have to query for those features that contain both conditions in the table.

A subset query for those meeting the first condition on the shape_area field will give you the undeveloped parcel on the flood plain that are greater than your specified area.

Of course... shape_area will be in the units of your data set, which should be in a projected coordinate system.  If they are decimal degrees, then you have a few hoops to go through to but

Calculate Geometry Attributes—Data Management toolbox | ArcGIS Desktop 

has an option to calculate the geometry of your features in acres