Earthworm abundances were tracked from 1997 to 2012 in established tillages (since 1983) and recently imposed tillages (since 1997) from a Brookston clay loam soil (Orthic Humic Gleysol) at Woodslee, ON. The tillages included the following systems: long-term fall moldboard plowing (CT83) and its 1997 conversion to no tillage (NT97-CT83), long-term no tillage (NT83) and its conversion to moldboard plowing (CT97-NT83), long-term ridge tillage (RT83) and its conversion to moldboard plowing (CT97-RT83), and long-term bluegrass sod (BG83) and its conversion to moldboard plowing (CT97-BG83). Lumbricus terrestris and Aporrectodea turgida were the most abundant of six species identified. The NT83 system had the greatest earthworm numbers except for 2012 when RT83 had equal abundance because of increased Ap. turgida juveniles. Populations in NT97-CT83 increased significantly from 1997 to 2012 because of reduced mechanical disturbance and greater surface residues. During 1997, 1999, and 2003, mean abundance in CT97-BG83 was not different from that of BG83, which likely occurred because buried sod continued to provide ample food. The CT97-RT83 system showed a decline in earthworm populations relative to RT83. The CT97-NT83 treatment had the most significant earthworm decline, reflecting a substantial increase in soil disturbance. Characterizing tillage system effects on earthworm dynamics (e.g., diversity, occurrence, adult, and juvenile abundance) will provide essential data for landscape models.