Google’s slogan may be don’t be evil, but a growing chorus of antitrust regulators in the United States and Europe want to know if the company has lived up to that creed.

This week, those concerns — especially whether Google gives its own businesses preferred placement in search results, thwarting competition and harming consumers — will have their most public airing to date, when Google’s chairman, Eric E. Schmidt, testifies before a Senate antitrust panel. Some of Google’s competitors will also testify.

The Senate proceeding is just one of an array of inquiries into Google’s behavior by various federal and state authorities in this country, as well as by regulators in Europe and Asia. And though the company and the times are different, there are echoes of a hearing before the same Senate body, the Judiciary antitrust subcommittee, 13 years ago and the last sweeping antitrust investigation of an American technology powerhouse, Microsoft. Later, the federal government, joined by 20 states, filed suit against Microsoft.

“Google is a great American success story, but its size, position and power in the marketplace have raised concerns about its business practices, and raised the question of what responsibilities come with that power,” said Senator Richard Blumenthal, Democrat of Connecticut, who is a member of the antitrust subcommittee and who as the attorney general of Connecticut played a leading role among the states that sued Microsoft.