| SC 13G | 2010-02-10 | Cortina Asset Management, LLC | PSYCHEMEDICS CORP | 447,397 | 8.6% | EDGAR |
| SC 13G | 2010-01-07 | ROYCE & ASSOCIATES LLC | PSYCHEMEDICS CORP | 598,231 | 11.5% | EDGAR |
| SC 13G/A | 2009-06-10 | LORD ABBETT & CO LLC | PSYCHEMEDICS CORP | 198,192 | 3.4% | EDGAR |
| SC 13G/A | 2009-02-17 | DISCOVERY EQUITY PARTNERS, LP | PSYCHEMEDICS CORP | 212,036 | 4.1% | EDGAR |
| SC 13G/A | 2009-02-13 | RENAISSANCE TECHNOLOGIES LLC | PSYCHEMEDICS CORP | 321,000 | 6.2% | EDGAR |
| SC 13G/A | 2009-02-13 | LORD ABBETT & CO LLC | PSYCHEMEDICS CORP | 436,385 | 8.4% | EDGAR |
| SC 13G | 2009-01-09 | Cortina Asset Management, LLC | PSYCHEMEDICS CORP | 442,070 | 8.5% | EDGAR |
| SC 13G/A | 2008-02-14 | ASHFORD CAPITAL MANAGEMENT INC | PSYCHEMEDICS CORP | - | - | EDGAR |
| SC 13G/A | 2008-02-14 | Discovery Group I, LLC | PSYCHEMEDICS CORP | 291,545 | 5.6% | EDGAR |
| SC 13G | 2008-02-14 | LORD ABBETT & CO LLC | PSYCHEMEDICS CORP | 398,900 | 7.6% | EDGAR |
| SC 13G | 2008-02-13 | RENAISSANCE TECHNOLOGIES LLC | PSYCHEMEDICS CORP | 270,000 | 5.2% | EDGAR |
| SC 13G | 2008-01-25 | Cortina Asset Management, LLC | PSYCHEMEDICS CORP | 395,924 | 7.6% | EDGAR |
| SC 13G | 2007-08-16 | Discovery Group I, LLC | PSYCHEMEDICS CORP | 276,538 | 5.3% | EDGAR |
| SC 13G/A | 2007-02-13 | ASHFORD CAPITAL MANAGEMENT INC | PSYCHEMEDICS CORP | 339,700 | 6.6% | EDGAR |
| SC 13G/A | 2007-02-13 | CHRISTOPH RICHARD T | PSYCHEMEDICS CORP | 0 | 0.0% | EDGAR |
| SC 13G/A | 2006-06-08 | Cortina Asset Management, LLC | PSYCHEMEDICS CORP | 566,131 | 11.0% | EDGAR |
| SC 13G | 2006-02-13 | ASHFORD CAPITAL MANAGEMENT INC | PSYCHEMEDICS CORP | 330,300 | 6.4% | EDGAR |
| SC 13G/A | 2006-02-09 | FEINBERG JEFF | PSYCHEMEDICS CORP | 0 | 0.0% | EDGAR |
| SC 13G | 2006-02-08 | Cortina Asset Management, LLC | PSYCHEMEDICS CORP | 383,464 | 7.4% | EDGAR |
| SC 13G/A | 2006-01-27 | CHRISTOPH RICHARD T | PSYCHEMEDICS CORP | 246,725 | 4.8% | EDGAR |