Pledges do not post, rather pledge installments post a separate transaction to the General Ledger, one for each fiscal period (month).  (Note: To post the pledge in one transaction, please refer to How can I post a pledge without listing all of the installments?)

The installments post to the account number defined on the fund record for Pledge Current or Pledge Future:
Pledge Current - Pledge installments which fall within the current fiscal year
Pledge Future - Pledge installments which fall within next fiscal year

Whether it posts to Pledge Current or Pledge Future depends on the fiscal year ending period defined in Configuration > General in The Raiser's Edge.

Here is an example of the Pledge Current and Pledge Future posting:
Let's use a $10,000 pledge with a date of 5/1/2015 that has a schedule of ten annual installments (i.e., $1000 per year for ten years). Today is 5/1/2015 so we're in the 2015 fiscal year. Our fiscal year ends in December (as set at Config > General) for a fiscal year that is the same as a calendar year.

The pledge installment schedule creates as follows:
1)5/1/2015$1000.00 6)5/1/2020$1000.00
2)5/1/2016$1000.00 7)5/1/2021$1000.00
3)5/1/2017$1000.00 8)5/1/2022$1000.00
4)5/1/2018$1000.00 9)5/1/2023$1000.00
5)5/1/2019$1000.00 10)5/1/2024$1000.00
Installment #1 will post to Pledge Current as its installment date is within the current fiscal year.
Installments #2 - #10 will post to Pledge Future as these installment dates are after the current year.

Note on Pledge Payments:
Pledge payments post separately from the original pledge installments, following the payment type entered on the payment (Pay-Cash, Pay-Stock/Property, Pay-Gift-in-Kind, Pay-Other, etc.). For a list of General Ledger accounts normally used for Raiser's Edge funds, refer to What debit and credit accounts are used for funds when posting to the General Ledger?.

Advanced explanation on the account set-up:
NOTE: This is provided to illustrate the movement of transactions within the General Ledger. Blackbaud cannot advise "which account" to select in your Raiser's Edge / General Ledger. Please consult with your accountant or other financial adviser regarding your organization's unique accounting needs.

Here is a typical set-up:
 Gift Type
 Debit Account
 Credit Account
 Pledge - Current
 Asset - A/R (Pledges Receivable Summary)
 Revenue – Pledges CY
 Pledge - Future
 Asset - A/R (Pledges Receivable Summary)
 Revenue – Pledges FY
A typical set-up is to setup a pledge to post its Debit side to a AR Summary account. An AR summary account would be a temporary holding place. The Credit side would be a Revenue account. When the payment is made and applied it would Debit an Asset account (Cash account as it’s money coming in) and Credit the AR Summary account. This would wash the money out of the Summary account (remember it’s a temporary holding place) therefore leaving the money Debit in the Asset account and Credit the Revenue account.
In a basic T chart:
Pledge InstallmentAR Summary AccountRevenue Account
Payment applied to installmentRevenue AccountAR Summary Account
ResultsAsset AccountRevenue Account
Notice that the AR Summary account is washed out once the payment is applied.