ATD Core4 runs September 29 to October 1, 2026 at the Indiana Convention Center. The venue forecasts 1,000 attendees. If you are the organiser holding the rooms for that group, the block is yours to build.
What the venue publishes
The Association for Talent Development holds Core4 at 100 South Capitol Ave, Indianapolis, IN 46225. The run is September 29 to October 1, 2026, and the venue lists a forecast attendance of 1,000.
Core4 is a conference for building and refining the core skills learning and development professionals need. Its sessions are built to send attendees home with skills they can apply in their work.
The downtown room supply
Four published numbers shape a block in Indianapolis. Downtown holds 7,100 hotel rooms. Skywalks connect 4,700 of those rooms to the Convention Center. Downtown holds 200 restaurants within walking distance. Indianapolis International Airport sits 15 minutes from downtown.
Those 4,700 rooms sit on a covered route to the show floor. Attendees reach session rooms without crossing a street.
Size the block from confirmed registrations
Start at 1,000 and work down to the rooms you will pay for. Subtract local attendees who sleep at home. Subtract attendees who share a room. Subtract anyone booking a single day.
Add the rooms your speakers, staff and exhibitors need. Add one room per night for the on-site contact.
Ask the sales manager for three figures on the nights of Monday September 28, Tuesday September 29 and Wednesday September 30: rooms available across the block, the rate at each tier, and the attrition threshold.
A block below your need pushes late registrants into the open market. A block above your need leaves you paying attrition on rooms nobody filled.
Send the rooming list to a written deadline
The contract names a rooming-list due date. Ask for that date in writing at signature, along with the name and email of the person who receives the file.
Build the file as one row per guest with arrival and departure dates. Send it on the date the property names, then send an updated file at each registration milestone. The property rebuilds its inventory from the file it holds.
Ask early how the property wants the file: spreadsheet, portal upload or a template of its own. A file in the wrong format sits in an inbox.
How the release date works
The release date returns your unsold rooms to general inventory. After that day the property sells those rooms to anyone, and your late registrants book from the same pool as the public.
Ask for the release date, the time of day it takes effect, and the person authorised to extend it. Ask whether the property will hold the block open when your count sits close to the total.
Ask whether rooms you release before the release date still count in the attrition calculation. Put the answer in writing.
Parking and early arrivals
Ask what the group rate covers in the garage. Ask whether it covers overnight parking, day use, or a fixed number of vehicles. Ask for the garage address and the posted clearance height, then carry the answer into your attendee email.
Core4 opens on the morning of Tuesday, September 29. Hotel check-in desks open in the afternoon. Ask for early check-in on arrival day, ask for bag storage from the morning, and ask whether the front desk can issue keys in one batch to your group contact.
Ask the same questions about departure morning. A luggage room on the last day keeps your group in the closing session.
The clause to confirm in writing
One paragraph decides the shape of the whole block. Ask the sales manager to state the release date, the rooming-list deadline and the attrition formula in a single written confirmation, then read the reply before you sign.
The clause to confirm is the release date with its attrition condition attached. A release date standing alone leaves two documents disagreeing about the same rooms.
Send that request by email and keep the reply with the signed contract.