I apologize for the length of this, but I''ve spent something like 12 solid hours at the keyboard trying to understand how this works, and I didn''t want to bother people in IRC anymore. I have a number of model classes, but the two that are relevant are App and Member. An App (Application is a reserved word not mentioned in the Wiki, so I had to choose something else) has zero or more Members associated with it. Zero is a possibility because we may redirect the user elsewhere before we even get to the ''list the household members'' step. I''ve been asked to design this system for maximum input speed. This particular controller, at least, will be used for back-office work, with users entering 1000 ''apps'' in a row as quickly as possible. I''m having two problems that I believe revolve around the same misunderstanding on my part: 1. The code I''m going to link to below does create the proper number of Member objects the first time through, and if I enter some fake test values that satisfy all the validation requirements, all is well, the Members get saved to the database, etc, etc. However, if there are errors, and I need to send them back to the new_members action, I can''t get the @members instance variable repopulated in such a way that it will re-display the information on the form. All the fields display as blanks. 2. When I need to display errors for a :partial :collection, what is the intended method? error_messages_for and its siblings are ''hard-coded'' to look for an instance variable. <%= error_messages_for ''app'' %> functions because @app exists. However, <%= error_messages_for ''member'' %> on the partial subform doesn''t work because @member does not exist. member is name registered in the local scope, not at the instance level. As you can see in the code below, I''ve got some temporary hack-job code that just checks the member.errors.count value ''by hand''. If I want to highlight fields with that technique, though, I''d have to write that for every column in the grid. In Java land, I normally have a separate ''form bean'' that has no knowledge of my model object, even if it contains mostly the same properties. That''s a lot of extra work, but it does make it relatively straightforward to enumerate errors on a collection like this. I couldn''t find any treatment of this in the Rails book. Am I just making life hard for myself, or is there a hidden mystery I need to be initiated into? Thanks, --Wilson. Sections of the code in question can be found here: http://supremetyrant.com/misc/rails_collection_woes.txt If you''d like more, or the database schema, etc, just let me know.