Pasture access can help prevent lameness and facilitate the expression of estrus but providing access to quality pasture is not always feasible. An alternative form of outdoor access is a deep-bedded pack, but it is unknown if access to an outdoor open pack is beneficial in these ways. The aims of this study were to investigate if access to an outdoor open pack can: 1) prevent the development of lameness, and 2) facilitate the expression of estrus behavior. A total of 36 cows were enrolled directly after calving and randomly assigned to either the OUTDOOR or INDOOR treatment and followed for a total of 12 weeks. All cows were housed in the same pen, but only OUTDOOR cows had access to an outdoor open pack. Each week, cows were gait scored from video observations. Cow behavior in the pen and on the outdoor pack was continuously followed by video recordings. Following an alert from the activity monitoring system, cows were checked for the presence of a preovulatory follicle and the absence of a mature corpus luteum (CL) by rectal ultrasonography following milking as well as 48 h and 7 d thereafter to confirm ovulation. Both suspected estrus and false alerts were scanned 7 d post-alert to confirm estrus classification (i.e., if the alert was correctly classified as a true or false estrus). For each true estrus event, the number of visits to the outdoor pack by OUTDOOR cows was investigated. The effect of treatment on gait score was assessed using a mixed model with treatment specified as fixed effect and cow as repeated effect. The effect of estrus status on visits to the outdoor pack was assessed using a mixed model with estrus status (i.e., in estrus or not) as fixed effect. No effect of treatment was found on mean gait score: INDOOR: 2.46 ± 0.15; OUTDOOR: 2.61 ± 0.15, but OUTDOOR cows visited the outdoor pack more often on days when they were in estrus (1.78 vs 6.07 visits/d). These results indicate that access to an outdoor pack has a positive effect on the expression of estrus behavior for freestall-housed dairy cows.