The paper updates information from EPA tests of indoor radon reduction techniques on 38 houses in the Reading Prong area of eastern Pennsylvania. All were basement houses with hollow-block or poured-concrete foundation walls. The reduction approaches tested in most houses involved active soil ventilation, including: suction on the footing drain tile system; suction under the concrete slabs, using pipes inserted through the slabs from inside the houses; and ventilation of the void network inside hollow-block foundation walls. Heat recovery ventilators (HRVs) were tested in three houses. Current results confirm that, for the houses tested, drain tile suction appears consistently able to provide high radon reductions when a complete loop of drain tile exists, often reducing high-radon-level houses to 4 pCi/l (148 Bq/cu m) and less. Sub-slab suction (with pipes through the slab) can also provide high reductions if enough suction pipes are located properly. Placing one or more sub-slab suction pipes near each perimeter wall appears to aid in treating the major soil gas entry routes, although fewer pipes can sometimes give high reductions if conditions are favorable. Ventilation of block wall voids can be effective if major wall openings can be adequately closed, and if there are no major slab-related entry routes remote from the walls.