| | | | | | | | | | |  | Major Transactions |
| | | | Thursday, October 6th, 1966 | | Signed 1B F. Torre to a 1-year contract extension worth a total of $300,000. |
| Tuesday, September 6th, 1966 | | Signed RF W. Herzog to a 2-year contract extension worth a total of $940,000. |
| Thursday, September 1st, 1966 | | Placed MR B. Faul on the active roster. | | Activated MR B. Faul from the 60-day disabled list. | | Purchased the contract of LF A. Kosco from Triple A Denver. |
| Monday, August 1st, 1966 | | MR T. Fletcher was designated for assignment and placed on waivers. |
| Saturday, April 23rd, 1966 | | Signed SP O. Pena to a 1-year contract extension worth a total of $26,241. |
| Friday, February 11th, 1966 | | Purchased the contract of LF A. Kosco from Triple A Denver. |
| Thursday, January 27th, 1966 | | Placed 2B D. McAuliffe on the active roster. |
| Wednesday, January 19th, 1966 | | Placed MR D. Green on the active roster. |
| Tuesday, December 28th, 1965 | | Signed free agent 2B D. McAuliffe to a 3-year contract worth a total of $1,050,000. |
| Monday, December 20th, 1965 | | Signed free agent MR D. Green to a 1-year contract worth a total of $44,800. |
| Wednesday, December 15th, 1965 | | Placed SP H. Woodeshick on the active roster. | | Placed 1B R. Sievers on the active roster. | | Placed SS R. Amaro on the active roster. |
| Saturday, December 11th, 1965 | | Signed free agent SS R. Amaro to a 1-year contract worth a total of $65,000. |
| Tuesday, December 7th, 1965 | | Signed free agent SP H. Woodeshick to a 3-year contract worth a total of $2,400,000. |
| Saturday, December 4th, 1965 | | Signed free agent 1B R. Sievers to a 1-year contract worth a total of $95,000. |
| Wednesday, December 1st, 1965 | | Drafted MR B. Anderson in the 1965 rule 5 draft (Pick 7, Round 1, 7th overall Pick). |
| Thursday, November 25th, 1965 | | Placed SP C. Short on the active roster. |
| Tuesday, November 16th, 1965 | | LF G. Alusik becomes a free-agent. | | MR J. Purdin received a 1-year contract through automatic renewal worth a total of $24,774. | | MR R. Duren becomes a free-agent. | | SP T. Bowsfield becomes a free-agent. | | C J. French received a 1-year contract through automatic renewal worth a total of $24,774. | | 3B S. Boros becomes a free-agent. | | LF R. White received a 1-year contract through automatic renewal worth a total of $24,774. | | MR L. Bearnarth received a 1-year contract through automatic renewal worth a total of $24,774. | | SP M. Lolich received a 1-year contract through automatic renewal worth a total of $24,774. | | SP E. Fisher becomes a free-agent. | | MR G. Richardson received a 1-year contract through automatic renewal worth a total of $24,774. | | MR B. Faul received a 1-year contract through automatic renewal worth a total of $24,774. | | 3B D. Buddin becomes a free-agent. | | 3B B. Harrelson received a 1-year contract through automatic renewal worth a total of $24,774. | | Traded nothing to the Kansas City Athletics, getting 28-year old starting pitcher C. Short in return. |
| Saturday, November 13th, 1965 | | C T. McCarver received a 1-year contract through arbitration worth a total of $267,948. | | RF B. Morton received a 1-year contract through arbitration worth a total of $59,340. | | CL B. Humphreys received a 1-year contract through arbitration worth a total of $163,712. | | 2B J. Wood received a 1-year contract through arbitration worth a total of $34,272. |
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