Back Cover:
Includes expanded Mishap and Events tables for seven of the core careers in the Traveller Main Book, and two alternative Life and Unusual Event tables for use during character generation.
From Table of Contents:
Expanded Tables: Agent, Drifter, Entertainer, Merchants, Nobility, Rogue, Scholar
New Careers: Adventurer, Bounty Hunter, Clergy, Colonist, Corporate Citizen, Militant Religious, Space Patrol, Worker
User Summary:
Expansion adding several new careers, and providing additional mishaps and events tables for seven of the 13 core book careers.
This is a "drop in an go" type supplement; it doesn't introduce any sweeping change, but GM's don't need to worry about power creep, and it makes no actual changes to mechanics of the game. The additional careers open the game to a number of additional settings adaptations.